JP2021022455A - Determination device, power supply system equipped with determination device, and determination method - Google Patents

Abstract

To provide a determination device capable of uniformly determining deterioration for determining replacement of a storage battery even for power storage batteries having different applications or specifications.SOLUTION: A deterioration determination device (100) includes a deterioration determination parameter acquisition unit (111) that acquires EMAX and EMIN from the specifications of a power storage battery (22), and acquires the values of E1, E2, P1, and P2 from a data storage unit (120), an internal resistance value calculation unit (112) that calculates R1 and R2, and a determination formula feasibility determination unit (113) that determines that the power storage battery (22) has deteriorated when at least one of the following (Equation 1) and (Equation 2) holds, and determines that the power storage battery (22) has not deteriorated when neither of the following (Equation 1) and (Equation 2) holds. (Equation 1) EMAX-E1≤α×P1/E1×R1. (Equation 2) E2-EMIN≤β×P2/E2×R2.SELECTED DRAWING: Figure 1

Description

The present invention relates to a battery deterioration determination device for determining a deterioration state of a storage battery.

Techniques for determining a deteriorated state of a storage battery are disclosed in, for example, Patent Documents 1 to 4. In the technique disclosed in Patent Document 1, the circuit parameters of the electrically equivalent circuit at the end of charging or the end of discharging of the secondary battery are calculated based on the transient response data of the secondary battery, and based on the circuit parameters. Diagnose the deterioration of the secondary battery. In the technique disclosed in Patent Document 2, the maximum current value at the time of charging / discharging in the lithium ion secondary battery is calculated when the time rate is 5 C or more and the battery surface temperature of the lithium ion secondary battery is 25 ° C. or less. The internal resistance of the lithium ion secondary battery is compared with the internal resistance threshold Ds1. In the technique disclosed in Patent Document 2, when the internal resistance becomes larger than the internal resistance threshold value Ds1, it is determined that the lithium ion secondary battery has deteriorated.

In the technique disclosed in Patent Document 3, the reference internal resistance, which is a reference in advance at the initial stage, the middle stage of use, and the final stage of use of the lithium ion battery, is compared with the actual internal resistance acquired during the charging / discharging operation of the lithium ion battery. Then, the amount of change in internal resistance is obtained. In the technique disclosed in Patent Document 3, the degree of deterioration of the lithium ion battery is determined based on the obtained amount of change in internal resistance. In the technique disclosed in Patent Document 4, the value of the ratio of the internal resistance at the time of discharging to the internal resistance at the time of charging the secondary battery is calculated, and when the value of the ratio drops below a predetermined value, the internal resistance It is determined that the battery has risen temporarily, and the temporary deterioration state of the secondary battery is detected.

Japanese Unexamined Patent Publication No. 2017-16991 (published on January 19, 2017) Japanese Unexamined Patent Publication No. 2013-125713 (published on June 24, 2013) JP-A-2015-45523 (March 12, 2015) Japanese Unexamined Patent Publication No. 2011-158267 (published on August 18, 2011)

However, the above-mentioned prior art has the following problems. In Patent Document 1, the specific deterioration judgment criteria for internal resistance are not clear. Further, also in Patent Document 2, since the calculation method of the internal resistance threshold value Ds1 is not clarified, the deterioration determination standard is not clear.

Further, in Patent Document 3, the reference internal resistance is set based on the initial value, but since the performance of the lithium ion battery required for each operation is different, the reference internal resistance specified based on the initial value is used. Based on the judgment, it does not mean that the lithium-ion battery does not need to be used. That is, in the technique described in Patent Document 3, it is necessary to determine an appropriate reference internal resistance for each application.

Further, the technique disclosed in Patent Document 4 aims at discriminating a transient and temporary increase in internal resistance to prevent further deterioration of the secondary battery, and is an irreversible increase in internal resistance, that is, , It does not determine the deterioration that affects the judgment as to whether or not the secondary battery needs to be replaced. Furthermore, when a lithium-ion battery is used as the secondary battery, the internal resistance and discharge during charging have different characteristics for each battery product with respect to the lithium-ion battery in which various materials can be selected for the positive electrode, negative electrode, electrolyte, etc. The method of determining deterioration based on the ratio to the internal resistance of time is not general-purpose.

The storage battery used for output smoothing that suppresses fluctuations in the power generation output of renewable energy frequently repeats intense charging and discharging. Since charge / discharge control depends on fluctuations in the power generation output of renewable energy, it is difficult to control the charge / discharge current according to the deterioration state of the storage battery, and the operation is stopped after grasping the deterioration state of the storage battery. Knowing or predicting the time to come is extremely important.

In addition, if the operation is stopped due to deterioration of the storage battery and the power generation output of renewable energy cannot be smoothed, the generated power of renewable energy cannot be output to the power system, so only the economic loss of the power generation establishment Not only the loss is large in terms of environment. For this reason, it is important to determine the deterioration of the storage battery and replace the storage battery appropriately before the operation is stopped.

The present invention has been made in view of the above-mentioned conventional problems, and is a determination device capable of uniformly determining deterioration for determining replacement of a storage battery even for storage batteries having different applications or specifications. The purpose is to realize.

In order to solve the above problems, the determination device according to one aspect of the present invention includes a storage battery for storing the power generated by the renewable energy power generation system, and the rate of change of the power output to the power system is predetermined. A determination device for determining deterioration of the storage battery provided in a power storage system of a type in which the storage battery repeatedly charges and discharges and suppresses output fluctuation of the power output to the power system so as to fall within the range. The _EMAX and _EMIN described in (Equation 1) and (Equation 2) are obtained from the specifications of the storage battery, and E ₁ , E ₂ , P ₁ and P ₂ described in the following (Equation 1) and (Equation 2) are obtained. Deterioration determination parameter acquisition unit that acquires the value of from the data storage unit that stores the data related to the charge / discharge behavior of the storage battery in a predetermined period, and R ₁ and R described in the following (Equation 1) and (Equation 2). _When the internal resistance value calculation unit for calculating ₂ and at least one of the following (Equation 1) and (Equation 2) are satisfied, the storage battery is deteriorated, and any of the following (Equation 1) and (Equation 2) If the above is not satisfied, the storage battery is characterized by including a determination formula feasibility determination unit for determining that the storage battery has not deteriorated.

(Equation 1) ... E _MAX- E ₁ ≤ α x P ₁ / E ₁ x R ₁
(Equation 2) ... E _2- E _MIN ≤ β x P ₂ / E ₂ x R ₂
E _MAX : Upper limit voltage set as the specification of the storage battery E _MIN : Lower limit voltage set as the specification of the storage battery E ₁ : Maximum SOC among SOCs (State Of Charge) of the storage battery changing in a predetermined period Corresponding maximum value of open circuit voltage (Open Circuit Voltage) E ₂ : Minimum value of open circuit voltage corresponding to the minimum SOC among the SOCs of the storage battery that changes in a predetermined period P ₁ : Changes in a predetermined period Maximum value in the charging power of the storage battery P ₂ : Maximum value in the discharging power of the storage battery that changes in a predetermined period R ₁ : Internal resistance value when the storage battery is charged R ₂ : When the storage battery is discharged Internal resistance values α and β: Arbitrary values as safety margins According to the above configuration, the determination device is (1) the specifications of the storage battery actually used acquired by the deterioration determination parameter acquisition unit. , The standard based on the data related to the charge / discharge behavior of the storage battery during the predetermined period actually used, and (2) the internal resistance value calculated by the internal resistance value calculation unit based on the actual measurement data during charging and discharging of the storage battery. , The deterioration of the storage battery can be determined. As a result, even for storage batteries having different applications or specifications, deterioration determination for uniformly determining replacement of the storage battery can be performed.

Further, in the determination device, the internal resistance value calculation unit uses the I ₁ , I ₂ , I ₃ , I ₄ , U ₁ , U ₂ , U ₃ and U described in the following (Equation 3) and (Equation 4). ₄ may be acquired from the data storage unit, the R ₁ may be calculated based on the following (Equation 3), and the R ₂ may be calculated based on the following (Equation 4).

(Equation 3) ... (U _2- U ₁ ) / (I _2- I ₁ )
(Equation 4) ... (U _3- U ₄ ) / (I _4- I ₃ )
U ₁ ... The storage battery is charged with a constant current value I _{1 for a} first predetermined time from a standby state in which charging / discharging is not performed, and the current value I ₁ is energized immediately before the charging is completed. The voltage value of the storage battery measured in the state of U ₂ ... From the standby state in which the storage battery is not charged or discharged, the first predetermined time is set by a constant current value I ₂ larger than the current value I _1. The voltage value of the storage battery measured in a state where the current value I ₂ is energized immediately before the charging is completed. U ₃ ... From the standby state in which the storage battery is not charged or discharged. The voltage value of the storage battery measured in a state where the current value I ₃ is energized immediately before the end of the discharge after discharging for the second predetermined time according to the constant current value I ₃ U ₄ ... With respect to the storage battery. From the standby state where charging and discharging are not performed, the current value I ₄ larger than the current value I ₃ is used to discharge for the second predetermined time, and the current value I ₄ is energized immediately before the end of the discharging. Voltage value of the storage battery measured in the state of being in the state According to the above configuration, the internal resistance value calculation unit can easily calculate the internal resistance value by the DC current before conversion to AC, so that the internal resistance value can be easily calculated. Can be calculated.

Further, in the determination device, the internal resistance value calculation unit obtains the equivalent circuit model related to the storage battery by fitting analysis based on the frequency dependence of the impedance measured by superimposing AC power on the storage battery. The resistance value in the equivalent circuit model may be at least one of R ₁ and R ₂ .

According to the configuration, the internal resistance value calculation unit can calculate the internal resistance value based on the frequency dependence of the impedance, so that the internal resistance value reflecting the deterioration of the electrode material constituting the storage battery is calculated. can do.

Further, in the determination device, the internal resistance value calculation unit obtained by fitting-analyzing an equivalent circuit model related to the storage battery based on the transient response characteristics of changes in current and voltage accompanying charging / discharging of the storage battery. The resistance value in the equivalent circuit model may be at least one of R ₁ and R ₂ .

According to the above configuration, the internal resistance value calculation unit can calculate the internal resistance value based on the transient response characteristics of the storage battery, which is simpler than the method based on the frequency dependence of the impedance. The internal resistance value that reflects the deterioration of the electrode material constituting the battery can be calculated.

Further, the determination device calculates the time dependence of the R _{1 from} the R ₁ and the corresponding battery operating time, and uses a first storage battery life estimation unit that estimates the time when the (Equation 1) is established. You may be prepared.

According to the arrangement, the the determination unit can grasp the time until the R ₁ and the storage battery by the time-dependent, which is calculated from the battery operation time corresponding thereto is deteriorated.

Further, the determination device calculates the time dependence of the R _{2 from} the R ₂ and the corresponding battery operating time, and uses a second storage battery life estimation unit that estimates the time when the (Equation 2) is established. You may have it.

According to the arrangement, the the determination unit can grasp the time until the R ₂ and battery by the time-dependent, which is calculated from the battery operation time corresponding thereto is deteriorated.

Further, the power supply system according to one aspect of the present invention includes the determination device, a current meter that measures the current value at the time of charging and discharging of the storage battery, and stores the measured current value in the data storage unit. A voltmeter that measures the voltage value during charging and discharging of the storage battery and stores the measured voltage value in the data storage unit, a power conditioner for the storage battery connected to the storage battery, and the renewable energy power generation system. It is characterized by being provided with a power conditioner for renewable energy power generation connected to a renewable energy power generation device that generates electric power in the above.

According to the above configuration, it is possible to realize a power supply system that achieves the above-mentioned effects.

Further, the determination method according to one aspect of the present invention includes a storage battery for storing the power generated by the renewable energy power generation system, and the change rate of the power output to the power system is within a predetermined range. This is a determination method for determining deterioration of the storage battery provided in a power storage system of a type in which the storage battery repeatedly charges and discharges and suppresses output fluctuation of the power output to the power system, and is the following (Equation 1) and (Equation 1). the _{E MAX} and _{E MIN} according to 2) were obtained from the specifications of the storage battery, the following (the value of formula 1) and _(E 1 according to equation _2), E 2, _{P 1} and _{P 2,} in a predetermined period The deterioration determination parameter acquisition step of acquiring the data related to the charge / discharge behavior of the storage battery from the data storage unit, and the internal resistance value for calculating R ₁ and R ₂ described in the following (Equation 1) and (Equation 2). When the calculation step and at least one of the following (Equation 1) and (Equation 2) are satisfied, the storage battery is deteriorated, and when neither of the following (Equation 1) and (Equation 2) is satisfied, the above The storage battery is characterized by including a determination formula feasibility determination step for determining that the storage battery has not deteriorated.

(Equation 1) ... E _MAX- E ₁ ≤ α x P ₁ / E ₁ x R ₁
(Equation 2) ... E _2- E _MIN ≤ β x P ₂ / E ₂ x R ₂
E _MAX : Upper limit voltage set as the specification of the storage battery E _MIN : Lower limit voltage set as the specification of the storage battery E ₁ : Maximum SOC among SOCs (State Of Charge) of the storage battery changing in a predetermined period Corresponding maximum value of open circuit voltage (Open Circuit Voltage) E ₂ : Minimum value of open circuit voltage corresponding to the minimum SOC among the SOCs of the storage battery that changes in a predetermined period P ₁ : Changes in a predetermined period Maximum value in the charging power of the storage battery P ₂ : Maximum value in the discharging power of the storage battery that changes in a predetermined period R ₁ : Internal resistance value when the storage battery is charged R ₂ : When the storage battery is discharged Internal resistance values α and β: Arbitrary values as safety margins According to the above configuration, the determination method is for uniformly determining the replacement of storage batteries even for storage batteries having different applications or specifications. Deterioration judgment can be performed.

According to one aspect of the present invention, it is possible to realize a determination device capable of uniformly determining deterioration for determining replacement of a storage battery even for storage batteries having different applications or specifications.

It is a figure which shows the schematic structure of the power supply system including the battery deterioration determination device which concerns on one Embodiment of this invention. It is a graph which shows the input / output power change in the simulated charge / discharge pattern. It is a graph which shows the charge rate in the simulated charge / discharge pattern. It is a graph which shows the DC internal resistance change in the 40 degreeC acceleration deterioration test in the simulated charge / discharge pattern. It is a figure which shows an example of the equivalent circuit model of the storage battery by the AC impedance method. It is a figure which shows an example of the equivalent circuit model of the storage battery in the transient response analysis method. It is a graph which shows an example of the measurement result of the AC impedance method.

Hereinafter, embodiments of the present invention will be described in detail. For convenience of explanation, the same reference numerals will be added to the members having the same functions as the members shown in the embodiment in the modified example of the embodiment, and the description thereof will be omitted as appropriate.

(Configuration of power supply system)
FIG. 1 is a diagram showing a schematic configuration of a power supply system 200 including a storage battery deterioration determination device according to an embodiment of the present invention. The power supply system 200 includes a power generation system 10, a power storage system 20, a deterioration determination device 100, a system cooperation facility 201, an ammeter 202, and a voltmeter 203.

The power generation system 10 (renewable energy power generation system) includes a power conditioner 11 for renewable energy power generation and a renewable energy power generation device 12. The renewable energy power generation device 12 generates power by using renewable energy such as solar power generation or wind power generation. The renewable energy power generation device 12 is, for example, a module in which a plurality of solar cells are connected, and receives sunlight to generate DC power. The power conditioner 11 for renewable energy power generation is connected to the renewable energy power generation device 12 and converts the DC power generated by the renewable energy power generation device 12 into AC power. Further, the power conditioner 11 for renewable energy power generation is connected to the grid cooperation facility 201 and the power storage system 20, and outputs the power generated by the renewable energy and converted into AC power to the grid cooperation facility 201 and the power storage system 20. To do.

The power storage system 20 is connected to the power generation system 10 and the grid cooperation equipment 201. The power storage system 20 includes a power conditioner 21 for a storage battery and a storage battery 22. The power storage system 20 is a storage battery system for smoothing the output of renewable energy.

The storage battery power conditioner 21 is connected to the storage battery 22 and controls the charging / discharging of the storage battery 22. The power conditioner 21 for a storage battery suppresses output fluctuations of the power output from the power generation system 10 so that the rate of change of the power output to the power system 301 falls within a predetermined range by repeatedly charging and discharging the storage battery 22. To do. The storage battery power conditioner 21 converts the alternating current output from the power generation system 10 into direct current power and charges the storage battery 22. Further, the storage battery power conditioner 21 converts the DC power discharged from the storage battery 22 into an AC current and outputs the DC power to the grid cooperation equipment 201. The storage battery 22 stores or discharges the electric power generated by the power generation system 10 and converted into DC electric power by the storage battery power conditioner 21 based on the instruction of the storage battery power conditioner 21. As the storage battery 22, a lithium ion battery can be optimally used.

The grid cooperation equipment 201 outputs the electric power output from the power generation system 10 or the electric power output from the power storage system 20 to the electric power system 301. The ammeter 202 measures the current value at the time of charging and discharging of the storage battery 22, and stores the measured current value in the data storage unit 120 described later. The voltmeter 203 measures the voltage value at the time of charging and discharging of the storage battery 22, and stores the measured voltage value in the data storage unit 120. The ammeter 202 and the voltmeter 203 have a function of accumulating data in the data storage unit 120 at predetermined time intervals. The function of the ammeter 202 and the voltmeter 203 may be possessed by the storage battery power conditioner 21.

(Deterioration judgment device)
The deterioration determination device 100 (determination device) determines the deterioration of the storage battery 22. The deterioration determination device 100 includes a control unit 110 and a data storage unit 120. The data storage unit 120 stores various programs executed by the control unit 110 and data used by the programs. In addition, the data storage unit 120 stores various measurement data that stores data related to the charge / discharge behavior of the storage battery 22 in a predetermined period.

The control unit 110 comprehensively controls each unit of the deterioration determination device 100. The function of the control unit 110 is realized, for example, by the CPU (Central Processing Unit) executing the program stored in the data storage unit 120. The control unit 110 includes a deterioration determination parameter acquisition unit 111, an internal resistance value calculation unit 112, a determination formula feasibility determination unit 113, a first storage battery life estimation unit 114, and a second storage battery life estimation unit 115. I have.

The deterioration determination parameter acquisition unit 111 acquires the upper limit voltage _EMAX and the lower limit voltage _EMIN from the specifications of the storage battery 22. The upper limit voltage E _MAX is the upper limit voltage set as the specification of the storage battery 22, and the lower limit voltage E _MIN is the lower limit voltage set as the specification of the storage battery 22. The upper limit voltage E _MAX and the lower limit voltage E _MIN are stored in the data storage unit 120 in advance, for example.

Further, the deterioration determination parameter acquisition unit 111 acquires the values of the maximum charge power P ₁ and the maximum discharge power P ₂ from the data storage unit 120. The maximum charge power P ₁ is the maximum value of the charge power of the storage battery 22 that changes in a predetermined period, and the maximum discharge power P ₂ is the maximum value of the discharge power of the storage battery 22 that changes in the predetermined period. Is. The predetermined period can be a period after the power storage system 20 is operated, and the period may be limited to the past one year or the like. Further, the maximum charge power P ₁ and the maximum discharge power P ₂ may be arbitrary values in case the data storage period is not sufficient. For example, the maximum charge power P ₁ and the maximum discharge power P ₂ are used for the storage battery. It may be the rated output of the power conditioner 21. Further, the maximum charge power P ₁ and the maximum discharge power P ₂ may be set to arbitrary values for one year after the operation, and then the values of the accumulated data may be adopted.

Further, the deterioration determination parameter acquisition unit 111 acquires the values of the maximum voltage E ₁ and the minimum voltage E ₂ from the data storage unit 120. The maximum voltage E ₁ is the maximum value of the open circuit voltage (OCV, Open Circuit Voltage) corresponding to the maximum SOC among the SOCs (charge rate, State Of Charge) of the storage battery 22 that changes in a predetermined period. The minimum voltage E ₂ is the minimum value of the open circuit voltage corresponding to the minimum SOC among the SOCs of the storage battery 22 that changes in the predetermined period. The open circuit voltage with respect to the SOC is determined by the specifications of the storage battery 22. The deterioration determination parameter acquisition unit 111 uses, for example, the open circuit voltage corresponding to the maximum SOC value and the minimum SOC value acquired from the correspondence table between the SOC and the open circuit voltage stored in the data storage unit 120. Is obtained as the maximum voltage E ₁ and the minimum voltage E ₂ .

The predetermined period can be a period after the power storage system 20 is operated, and the period may be limited to the past one year or the like. Further, the values of the maximum voltage E ₁ and the minimum voltage E ₂ may be arbitrary values in case there is not a sufficient data storage period. For example, the charge / discharge of the storage battery 22 accompanying the smoothing of the output of renewable energy power generation is simulated in advance, and the voltage corresponding to the maximum SOC at that time is the maximum voltage E ₁ and the voltage corresponding to the minimum SOC is the minimum voltage E _2. May be. Further, the maximum voltage E ₁ and the minimum voltage E ₂ may be set to arbitrary values for one year after the operation, and then the values of the accumulated data may be adopted.

The SOC of the storage battery 22 is calculated from the current capacity (Ah) that is charged and discharged to the storage battery 22 after the storage battery 22 is in a fully charged state (SOC 100%) or a completely discharged state (SOC 0%). Further, the storage battery 22 is placed in a standby state in which charging / discharging is not performed (a state in which SOC can be estimated from the open circuit voltage), and the SOC of the storage battery 22 is calculated from the current capacity charged / discharged in the storage battery 22 from that state. You may. Further, when the storage battery 22 is provided with a battery management system (BMS) or a battery management unit (BMU) and the SOC is calculated by the BMS or BMU, the value may be used.

(Internal resistance value calculation unit)
The internal resistance value calculation unit 112 calculates the charging internal resistance R ₁ and the discharging internal resistance R ₂ . The charging internal resistance R ₁ is the internal resistance value when the storage battery 22 is charged, and the discharging internal resistance R ₂ is the internal resistance value when the storage battery 22 is discharged.

The internal resistance value calculation unit 112 acquires the current value I ₁ , the current value I ₂ , the voltage value U ₁ , and the voltage value U ₂ from the data storage unit 120, and charges the internal resistance R based on the following (Equation 1). ₁ is calculated.

R ₁ = (U _2- U ₁ ) / (I _2- I ₁ ) ... (Equation 1)
Here, the voltage value U ₁ charges the storage battery 22 for the first predetermined time with a constant current value I ₁ from a standby state in which charging / discharging is not performed, and the current is generated immediately before the charging is completed. It is the voltage value of the storage battery measured in the state where the value I ₁ is energized. The voltage value U ₂ charges the storage battery 22 for a first predetermined time with a constant current value I ₂ larger than the current value I ₁ from a standby state in which charging / discharging is not performed, and the charging is completed. It is a voltage value of the storage battery measured in a state where the current value I ₂ is energized immediately before the current value I ₂ .

The internal resistance value calculation unit 112 while operating the storage battery 22 periodically calculates the charge internal resistance R _1. While operating the storage battery 22, the internal resistance value calculation unit 112 periodically adjusts the SOC and charges the storage battery 22 with the current value I ₁ and the current value I ₂ , whereby the voltage value U ₁ and the voltage value U ₂ are charged. Is acquired, and the current value I ₁ , the current value I ₂ , the voltage value U _1, and the voltage value U ₂ are stored in the data storage unit 120. The SOC is adjusted to be, for example, 50%. The internal resistance value calculation unit 112 calculates the charging internal resistance R ₁ based on the current value I ₁ , the current value I ₂ , the voltage value U _1, and the voltage value U ₂ stored in the data storage unit 120.

In order to improve the accuracy, the internal resistance value calculation unit 112 may calculate the charging internal resistance R ₁ of the following methods. That is, the storage battery 22 is charged for the first predetermined time with a constant current value I _1-1 different from the current value I ₁ and the current value I ₂ from the standby state in which charging / discharging is not performed, and the charging is performed. The voltage value U _1-1 is measured while the current value I _1-1 is energized immediately before the end of. The change in the voltage value with respect to the charging current is linearly approximated by the current value I ₁ , the current value I ₂ , the current value I _1-1 , the voltage value U ₁ , the voltage value U _2, and the voltage value U _1-1, and from the inclination thereof. method of calculating the charge internal resistance, may calculate the charging internal resistance R ₁ of a so-called V-I characteristic.

Further, the internal resistance value calculation unit 112 acquires the current value I ₃ , the current value I ₄ , the voltage value U ₃ , and the voltage value U ₄ from the data storage unit 120, and the inside of the discharge is based on the following (Equation 2). Calculate the resistance R ₂ .

R ₂ = (U _3- U ₄ ) / (I _4- I ₃ ) ... (Equation 2)
Here, the voltage value U ₃ discharges the storage battery 22 from a standby state in which charging / discharging is not performed to a constant current value I _{3 for a} second predetermined time, and the current is generated immediately before the discharge is completed. It is the voltage value of the storage battery measured in the state where the value I ₃ is energized. The voltage value U ₄ discharges the storage battery 22 from a standby state in which charging / discharging is not performed to a constant current value I ₄ larger than the current value I _{3 for a} second predetermined time, and the discharge ends. This is the voltage value of the storage battery measured in a state where the current value I ₄ is energized immediately before the discharge.

The internal resistance value calculation unit 112 periodically calculates the discharge internal resistance R ₂ while operating the storage battery 22. While operating the storage battery 22, the internal resistance value calculation unit 112 periodically adjusts the SOC and discharges the current value I ₃ and the current value I ₄ from the storage battery 22 to obtain the voltage value U ₃ and the voltage value U ₄ . Acquired, and stores the current value I ₃ , the current value I ₄ , the voltage value U _3, and the voltage value U ₄ in the data storage unit 120. The SOC is adjusted to be, for example, 50%. The internal resistance value calculation unit 112 calculates the discharge internal resistance R ₂ based on the current value I ₃ , the current value I ₄ , the voltage value U _3, and the voltage value U ₄ stored in the data storage unit 120.

Further, in order to further improve the accuracy, the internal resistance value calculation unit 112 may calculate the discharge internal resistance R ₂ by the following method. That is, the storage battery 22 is discharged for a second predetermined time from a standby state in which charging / discharging is not performed, with a constant current value I _3-1 different from the current value I ₃ and the current value I _4. The voltage value U _3-1 is measured while the current value I _3-1 is energized immediately before the end of. The change in the voltage value with respect to the discharge current is linearly approximated by the current value I ₃ , the current value I ₄ , the current value I _3-1 and the voltage value U ₃ , the voltage value U _4, and the voltage value U _3-1. The discharge internal resistance R ₂ may be calculated from a method of calculating the discharge internal resistance, so-called VI characteristics.

(Judgment formula feasibility judgment unit)
The determination formula feasibility determination unit 113 determines deterioration for determining replacement of the storage battery 22. The determination formula feasibility determination unit 113 determines that the storage battery 22 is deteriorated when at least one of the following (Equation 3) and (Equation 4) is satisfied. If neither of the following (Equation 3) and (Equation 4) is satisfied, the determination formula feasibility determination unit 113 determines that the storage battery 22 has not deteriorated.

E _MAX- E ₁ ≤ α x P ₁ / E ₁ x R ₁ ... (Equation 3)
E _2- E _MIN ≤ β x P ₂ / E ₂ x R ₂ ... (Equation 4)
Here, α and β are arbitrary values as the safety margin. The safety margin can be, for example, 10-20%, in which case α and β will be 1.1-1.2.

(1st storage battery life estimation unit)
The first battery life estimator 114, the time dependence of the charging internal resistance R _1, calculated from the battery operation time and its corresponding charge internal resistance R _1, wherein estimating the timing of (Equation 3) is satisfied The life of the storage battery 22 is estimated by A specific calculation example will be described later.

(Second storage battery life estimation unit)
The second battery life estimating unit 115, the time dependence of the discharge internal resistance R _2, calculated from the discharge internal resistance R ₂ and the battery operating time corresponding thereto, said estimating the timing of (Equation 4) is satisfied The life of the storage battery 22 is estimated by A specific calculation example will be described later.

(Effect of deterioration judgment device)
The deterioration determination device 100 is based on (1) the specifications of the storage battery 22 actually used acquired by the deterioration determination parameter acquisition unit 111 and the data related to the charge / discharge behavior of the storage battery 22 during the predetermined period of actual use. When at least one of the above (Equation 3) and the above (Equation 4) is satisfied by using the reference and (2) the charging internal resistance R ₁ and the discharging internal resistance R ₂ calculated by the internal resistance value calculation unit 112. , It is determined that the storage battery 22 has deteriorated and needs to be replaced. Therefore, according to the deterioration determination device 100, deterioration determination for uniformly determining replacement of the storage battery can be performed even for storage batteries having different applications or specifications. As a result, the replacement time of the storage battery 22 can be appropriately grasped, and the storage battery 22 can be replaced at an appropriate time.

Further, it becomes possible to easily obtain the deterioration determination standard of the storage battery 22. Further, the life of the storage battery 22 can also be estimated by the first storage battery life estimation unit 114 and the second storage battery life estimation unit 115.

(Example of deterioration judgment processing)
An example of a specific deterioration determination process will be described with reference to FIGS. 2 to 4. FIG. 2 is a graph showing changes in input / output power of the storage battery 22 in a simulated charge / discharge pattern described later. The horizontal axis of FIG. 2 shows the test time, and the vertical axis shows the charged and discharged power. In FIG. 2, the positive side of the vertical axis is the charging power, and the negative side is the discharging power. FIG. 3 is a graph showing SOC in a simulated charge / discharge pattern described later. The horizontal axis of FIG. 3 shows the test time, and the vertical axis shows the SOC.

An example of this deterioration determination process is the output power of power generation by charging and discharging the storage battery 22 so that the output change rate is within 18% / min of the rated output of photovoltaic power generation using the power generation output data of photovoltaic power generation. Based on the simulation results when smoothing is performed. In the example of this deterioration judgment process, five days, which is a typical charge / discharge pattern, is extracted from the data for one year based on the simulation result, and the integrated capacity and the discharge capacity, which are the sum of only the charge capacity for one day, and the discharge capacity. A simulated charge / discharge pattern was created so that the integrated capacity, which is the sum of only the sums, is almost the same. The patterns for the five days were combined according to the annual frequency of occurrence to obtain a simulated charge / discharge pattern for the storage battery 22. Further, as the storage battery 22, a charge / discharge test of a lithium ion battery cell applied for stationary use was carried out at 25 ° C.

(Parameter acquisition process for deterioration judgment)
Assuming that the photovoltaic power generation output is smoothed by repeating the above-mentioned simulated charge / discharge pattern according to the annual occurrence frequency, and assuming that the predetermined period is one year, the charge / discharge behavior of the simulated charge / discharge pattern is determined. The maximum charging power P ₁ of the storage battery 22 is 452 W of the pattern 1 from FIG. Similarly, from FIG. 2, the maximum discharge power P ₂ of the storage battery 22 is 452 W of the pattern 1. Therefore, the deterioration determination parameter acquisition unit 111 acquires 452 W as the maximum charge power P ₁ and 452 W as the maximum discharge power P ₂ from the data storage unit 120.

Further, from FIG. 3, the maximum SOC of the storage battery 22 is 44.4% of the pattern 1, and the minimum SOC is 13.7% of the pattern 1. As a result, the deterioration determination parameter acquisition unit 111 sets the voltages corresponding to SOC 44.4% and SOC 13.7% from the data storage unit 120 as the maximum voltage E ₁ and the minimum voltage E ₂ based on the characteristics of the storage battery 22. get. The deterioration determination parameter acquisition unit 111 acquires, for example, the maximum voltage E ₁ corresponding to SOC 44.4% as 3.86 V and the minimum voltage E ₂ corresponding to SOC 13.7% as 3.57 V.

Further, the deterioration determination parameter acquisition unit 111 acquires the upper limit voltage _EMAX and the lower limit voltage _EMIN of the storage battery 22 from the specifications of the storage battery 22. Deterioration determining parameter acquiring unit 111 acquires, for example, the upper limit voltage _{E MAX} of the storage battery 22 4.1 V, the lower limit voltage _{E MIN} as 3.0 V.

(Internal resistance value calculation process)
On the other hand, the internal resistance value calculation unit 112 adjusts the storage battery to SOC 50%, charges the storage battery with a current value corresponding to 0.5 C for 10 seconds, and records the voltage value immediately before the charging suspension in the data storage unit 120. Further, after providing a sufficient pause time, discharge is performed for 10 seconds with a current value corresponding to 0.5 C, and the voltage value immediately before the discharge pause is recorded in the data storage unit 120. After that, the internal resistance value calculation unit 112 performs the same charge / discharge with a current value corresponding to 2C with a sufficient pause time, and records the voltage value immediately before the charge / discharge in the data storage unit 120. The internal resistance value calculation unit 112, a current value corresponding to the voltage values and the C rate recorded in the data storage unit 120, the equation (1) and based on said equation (2), charging the internal resistance R ₁ and a discharge The internal resistance R ₂ is calculated. The internal resistance value calculation unit 112 calculates, for example, the charging internal resistance R ₁ to be 0.815 mΩ and the discharge internal resistance R ₂ to be 0.879 mΩ.

(Judgment formula feasibility judgment process)
From each calculation result, E _MAX- E ₁ is calculated as 0.24 V, and E _2- E _MIN is calculated as 0.57 V. Further, P ₁ / E ₁ × R ₁ is 0.095 V, P ₂ / E ₂ × R ₂ is 0.111 V, and when α and β are set to 1.1 in consideration of 10% as a safety margin. The above (Equation 3) and the above (Equation 4) do not hold. Therefore, in the example of this deterioration determination process, the determination formula feasibility determination unit 113 determines that the storage battery 22 has not deteriorated and does not need to be replaced.

(Example of life estimation processing)
An example of a specific life estimation process will be described with reference to FIG. To understand the degradation tendency of the battery 22, to implement the long-term tests with the simulated charge and discharge pattern under 40 ° C. environment periodically charging the internal resistance R ₁ and the discharge internal resistance R ₂ in the SOC 50% of the storage battery 22 It was measured. The result is FIG. 4, and FIG. 4 is a graph showing the change in DC internal resistance in the 40 ° C. accelerated deterioration test in the simulated charge / discharge pattern. In other words, FIG. 4 is a graph showing the dependence of the charge internal resistance R ₁ and the discharge internal resistance R _{2 on} the test time. The horizontal axis of FIG. 4 shows the test time, and the vertical axis shows the DC internal resistance.

From FIG. 4, the DC internal resistance after about 9400 hours have elapsed is calculated as 0.960 mΩ for the charge internal resistance R _{1 and} 1.054 mΩ for the discharge internal resistance R ₂ . At this time, P ₁ / E ₁ × R ₁ is 0.112 V, P ₂ / E ₂ × R ₂ is 0.133 V, and α and β are set to 1.1 in consideration of 10% as a safety margin. , The above (Equation 3) and (Equation 4) do not hold. Therefore, it can be determined that the storage battery 22 is not deteriorated and replacement is unnecessary after about 9400 hours have passed.

When the above (Equation 3) holds when α and β are 1.1, assuming that the maximum charge power P ₁ , the maximum discharge power P _{2, the} maximum voltage E ₁ , and the minimum voltage E ₂ do not change. The charging internal resistance R ₁ is 1.863 mΩ, and the discharge internal resistance R ₂ when the above (Equation 4) is satisfied is 4.093 mΩ. Assuming that the increase in internal resistance due to deterioration is proportional to the test time, the battery life can be estimated to be about 65880 hours from the linear linear line of the charging internal resistance in FIG. 65880 hours corresponds to about 7.5 years, and the life of the storage battery 22 is 7.5 years. In order to perform the life estimation process more accurately, it is desirable to consider changes in the maximum voltage E ₁ and the minimum voltage E ₂ due to the decrease in the capacity of the storage battery 22.

(Modification example)
A modified example of the present invention will be described below with reference to FIGS. 5 and 6. FIG. 5 is a diagram showing an example of an equivalent circuit model in the AC impedance method. FIG. 6 is a diagram showing an example of an equivalent circuit model in the transient response analysis method. For convenience of explanation, the same reference numerals will be added to the members having the same functions as the members described in the above embodiment, and the description will not be repeated.

The internal resistance value calculation unit 112 fits and analyzes the equivalent circuit model shown in FIG. 5 related to the storage battery 22 based on the frequency dependence of the impedance measured by superimposing AC power on the storage battery 22, and obtains the equivalent circuit. The resistance value in the model may be at least one of the charging internal resistance R ₁ and the discharging internal resistance R ₂ . A specific example is shown below.

FIG. 7 shows the real part and the imaginary part of the impedance Z measured by adjusting the storage battery 22 to SOC 50% and performing AC impedance measurement at a frequency of 10 kHz to 5 MHz. FIG. 7 is a graph showing an example of the measurement result of the AC impedance method. The vertical axis shows the imaginary part ImZ of impedance Z, and the horizontal axis shows the real part ReZ of impedance Z. As a result of performing fitting analysis on this measurement result with the equivalent circuit shown in FIG. 5, each equivalent circuit constant is shown below.

L: 1.0819 × 10-7 (H)
R ₁₁ : 0.000436 (Ω)
R ₁₂ : 0.000049 (Ω)
R ₁₃ : 0.000028 (Ω)
CPE ₁ : CPE index p 1, CPE constant T 25.537
R ₁₄ : 0.006388 (Ω)
Wz: 8.418 x 10-5 (Ω)
CPE ₂ : CPE index p 0.9921, CPE constant T 5.5793
Here, in FIG. 5, R ₁₁ is an ohmic resistor, R ₁₂ and R ₁₃ are reaction resistors, CPE ₁ and CPE ₂ are capacitance components that substitute for capacitors, and W _Z is a diffusion resistor. Further, L is an electrode terminal and a reactance component of the cable, and R ₁₄ is a resistance component of the electrode terminal and the cable. May be used as the ohmic resistor _{R 11} charge internal resistance _{R 1} and the discharge internal resistance _{R 2} of the storage battery 22 may be the _R 11 _{+ R} 12 _{+ R 13,} including reaction resistance as a charging internal resistance _{R 1} and the discharge internal resistance _{R 2} ..

Further, the internal resistance value calculation unit 112 fits and analyzes an equivalent circuit model in the transient response analysis method shown in FIG. 6 relating to the storage battery 22 based on the transient response characteristics of changes in the current and voltage accompanying charging and discharging of the storage battery 22. Then, the resistance value in the obtained equivalent circuit model may be at least one of the charging internal resistance R ₁ and the discharging internal resistance R ₂ . A specific example is shown below.

The equivalent circuit model shown in FIG. 6 is fitted and analyzed based on the transient response characteristics of changes in voltage and current when the storage battery 22 is adjusted to SOC 50% and charged / discharged in an arbitrary pattern including a current value of about 1 C rate. To do. An example of each equivalent circuit constant obtained from the result is shown below.

R _i: 0.000582 (Ω)
R ₂₁ : 0.000223 (Ω)
C ₂₁ : 2.91 x 104 (F)
R ₂₂ : 0.00260 (Ω)
C ₂₂ : 4.58 x 104 (F)
Here, in FIG. 6, _{R i} is the ohmic _{resistance, R 21} and _{R 22} is a reactive _{resistance, C 21} and _{C 22} are capacitance component. Also, _{I B} is the charging and discharging current, _{V B} is measured voltage, _{V O} is the open circuit _{voltage, V Z, V ZO, V} Z1, V Z2 is polarization voltage.

When the charge-discharge current _{I B} flows, the polarization voltage _{V Z0, V Z1, V Z2} and so that the total value of the open circuit voltage _{V 0} is the highest matching with the measured voltage _{V B,} the fitting analyzes each of the equivalent circuit constants Is determined by. The ohmic resistance R _{i of the} storage battery may be the charging internal resistance R ₁ and the discharging internal resistance R ₂ , and the R _i + R ₂₁ + R ₂₂ including the reaction resistance may be the charging internal resistance R ₁ and the discharging internal resistance R ₂ .

[Example of realization by software]
Control block of deterioration determination device 100 (in particular, deterioration determination parameter acquisition unit 111, internal resistance value calculation unit 112, determination formula feasibility determination unit 113, first storage battery life estimation unit 114, and second storage battery life estimation unit 115) May be realized by a logic circuit (hardware) formed in an integrated circuit (IC chip) or the like, or may be realized by software.

In the latter case, the deterioration determination device 100 includes a computer that executes instructions of a program that is software that realizes each function. The computer includes, for example, one or more processors and a recording medium that can be read by a computer that stores the program. Then, in the computer, the object of the present invention is achieved by the processor reading the program from the recording medium and executing the program. As the processor, for example, a CPU (Central Processing Unit) can be used. As the recording medium, in addition to a “non-temporary tangible medium” such as a ROM (Read Only Memory), a tape, a disk, a card, a semiconductor memory, a programmable logic circuit, or the like can be used. Further, a RAM (Random Access Memory) or the like for expanding the program may be further provided. Further, the program may be supplied to the computer via an arbitrary transmission medium (communication network, broadcast wave, etc.) capable of transmitting the program. It should be noted that one aspect of the present invention can also be realized in the form of a data signal embedded in a carrier wave, in which the program is embodied by electronic transmission.

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims, and the embodiments obtained by appropriately combining the technical means disclosed in the different embodiments. Is also included in the technical scope of the present invention.

10 Power generation system 11 Power conditioner for renewable energy power generation 12 Renewable energy power generation device 20 Power storage system 21 Power conditioner for storage battery 22 Storage battery 100 Deterioration judgment device (judgment device)
111 Deterioration judgment parameter acquisition unit 112 Internal resistance value calculation unit 113 Judgment formula feasibility judgment unit 114 1st storage battery life estimation unit 115 2nd storage battery life estimation unit 120 Data storage unit 200 Power supply system 202 Current meter 203 Voltmeter 301 Power System E _MAX upper limit voltage E _MIN lower limit voltage P ₁ maximum charge power P ₂ maximum discharge power E ₁ maximum voltage E ₂ minimum voltage

Claims (8)

It is equipped with a storage battery that stores the power generated by the renewable energy power generation system, and the storage battery is repeatedly charged and discharged so that the rate of change of the power output to the power system falls within a predetermined range, and is output to the power system. It is a determination device for determining deterioration of the storage battery provided in a power storage system of a type that suppresses fluctuations in the output of electric power.
The _EMAX and _EMIN described in the following (Equation 1) and (Equation 2) are obtained from the specifications of the storage battery, and the E ₁ , E ₂ , P ₁ and P described in the following (Equation 1) and (Equation 2) are obtained. A deterioration determination parameter acquisition unit that acquires the value of ₂ from a data storage unit that stores data related to the charge / discharge behavior of the storage battery in a predetermined period.
The internal resistance value calculation unit that calculates R ₁ and R ₂ described in (Equation 1) and (Equation 2) below, and
When at least one of the following (Equation 1) and (Equation 2) is satisfied, the storage battery is deteriorated, and when neither of the following (Equation 1) and (Equation 2) is satisfied, the storage battery is deteriorated. A determination device including a determination expression feasibility determination unit that determines that the determination formula is not established.
(Equation 1) ... E _MAX- E ₁ ≤ α x P ₁ / E ₁ x R ₁
(Equation 2) ... E _2- E _MIN ≤ β x P ₂ / E ₂ x R ₂
E _MAX : Upper limit voltage set as the specification of the storage battery E _MIN : Lower limit voltage set as the specification of the storage battery E ₁ : Maximum SOC among SOCs (State Of Charge) of the storage battery that changes in a predetermined period Corresponding maximum value of open circuit voltage (Open Circuit Voltage) E ₂ : Minimum value of open circuit voltage corresponding to the minimum SOC among the SOCs of the storage battery that changes in a predetermined period P ₁ : Changes in a predetermined period Maximum value in the charging power of the storage battery P ₂ : Maximum value in the discharging power of the storage battery that changes in a predetermined period R ₁ : Internal resistance value when the storage battery is charged R ₂ : When the storage battery is discharged Internal resistance values α and β: Arbitrary values as safety margins The internal resistance value calculation unit transfers I ₁ , I ₂ , I ₃ , I ₄ , U ₁ , U ₂ , U ₃ and U ₄ described in the following (Equation 3) and (Equation 4) from the data storage unit. The determination device according to claim 1, wherein the R ₁ is acquired, the R ₁ is calculated based on the following (Equation 3), and the R ₂ is calculated based on the following (Equation 4).
(Equation 3) ... (U _2- U ₁ ) / (I _2- I ₁ )
(Equation 4) ... (U _3- U ₄ ) / (I _4- I ₃ )
U ₁ : The storage battery is charged with a constant current value I _{1 for a} first predetermined time from a standby state in which charging / discharging is not performed, and the current value I ₁ is energized immediately before the charging is completed. Voltage value of the storage battery measured in the state of U ₂ : The first predetermined time by a constant current value I ₂ larger than the current value I ₁ from the standby state in which the storage battery is not charged or discharged. The voltage value of the storage battery measured in a state where the current value I ₂ is energized immediately before the charging is completed. U ₃ : From the standby state in which the storage battery is not charged or discharged. The voltage value of the storage battery measured in a state where the current value I ₃ is energized immediately before the end of the discharge after discharging for the second predetermined time with the constant current value I ₃ U ₄ : With respect to the storage battery. From the standby state where charging and discharging are not performed, the current value I ₄ larger than the current value I ₃ is used to discharge for the second predetermined time, and the current value I ₄ is energized immediately before the end of the discharging. The voltage value of the storage battery measured while it is The internal resistance value calculation unit
Based on the frequency dependence of the impedance measured by superimposing AC power on the storage battery, the equivalent circuit model related to the storage battery is fitted and analyzed, and the resistance value in the obtained equivalent circuit model is obtained in R ₁ and R. The determination device according to claim 1, wherein the determination device is at least one of the _two . The internal resistance value calculation unit
Based on the transient response characteristics, the changes in current and voltage associated with the charging and discharging of the storage battery are analyzed by fitting the equivalent circuit model of the storage battery, and the resistance values in the obtained equivalent circuit model are determined by R ₁ and R _2. The determination device according to claim 1, wherein the determination device is at least one of the above. It is characterized by having a first storage battery life estimation unit that calculates the time dependence of the R _{1 from} the R ₁ and the corresponding battery operating time and estimates the time when the above (Equation 1) is established. The determination device according to any one of claims 1 to 4. It is characterized by having a second storage battery life estimation unit that calculates the time dependence of the R _{2 from} the R ₂ and the corresponding battery operating time and estimates the time when the above (Equation 2) is established. The determination device according to any one of claims 1 to 4. The determination device according to any one of claims 1 to 6,
An ammeter that measures the current value during charging and discharging of the storage battery and stores the measured current value in the data storage unit.
A voltmeter that measures the voltage value during charging and discharging of the storage battery and stores the measured voltage value in the data storage unit.
A power conditioner for a storage battery connected to the storage battery and
A power conditioner for renewable energy power generation connected to a renewable energy power generation device that generates electric power in the renewable energy power generation system,
A power supply system characterized by being equipped with. It is equipped with a storage battery that stores the power generated by the renewable energy power generation system, and the storage battery is repeatedly charged and discharged so that the rate of change of the power output to the power system falls within a predetermined range, and is output to the power system. It is a determination method for determining deterioration of the storage battery provided in a power storage system of a type that suppresses fluctuations in the output of electric power.
The _EMAX and _EMIN described in the following (Equation 1) and (Equation 2) are obtained from the specifications of the storage battery, and the E ₁ , E ₂ , P ₁ and P described in the following (Equation 1) and (Equation 2) are obtained. A deterioration determination parameter acquisition step of acquiring the value of ₂ from a data storage unit that stores data related to the charge / discharge behavior of the storage battery in a predetermined period, and
The internal resistance value calculation step for calculating R ₁ and R ₂ described in (Equation 1) and (Equation 2) below, and
When at least one of the following (Equation 1) and (Equation 2) is satisfied, the storage battery is deteriorated, and when neither of the following (Equation 1) and (Equation 2) is satisfied, the storage battery is deteriorated. A determination method characterized in that it includes a determination formula feasibility determination step for determining that it does not exist.
(Equation 1) ... E _MAX- E ₁ ≤ α x P ₁ / E ₁ x R ₁
(Equation 2) ... E _2- E _MIN ≤ β x P ₂ / E ₂ x R ₂
E _MAX : Upper limit voltage set as the specification of the storage battery E _MIN : Lower limit voltage set as the specification of the storage battery E ₁ : Maximum SOC among SOCs (State Of Charge) of the storage battery that changes in a predetermined period Corresponding maximum value of open circuit voltage (Open Circuit Voltage) E ₂ : Minimum value of open circuit voltage corresponding to the minimum SOC among the SOCs of the storage battery that changes in a predetermined period P ₁ : Changes in a predetermined period Maximum value in the charging power of the storage battery P ₂ : Maximum value in the discharging power of the storage battery that changes in a predetermined period R ₁ : Internal resistance value when the storage battery is charged R ₂ : When the storage battery is discharged Internal resistance values α and β: Arbitrary values as safety margins

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