JP2014166042A - Power storage system with lead storage battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase a life of a lead storage battery for a power storage system with the lead storage battery.SOLUTION: After charging a lead storage battery 7 utilizing an external power source, discharging to a load system 3 starts at a discharge start time, a provision second SOC at which the discharge is to be stopped and a provision first SOC that is higher than the provision second SOC are set in advance, discharging is continued by adjusting a current so as to reach the provision second SOC at a discharge completion time when the provision first SOC is reached, and charging is started immediately after the discharging.

Description

  The present invention relates to a power storage system that charges and discharges using a lead storage battery.

Lead-acid batteries are used for various applications due to their high reliability. In recent years, lead-acid batteries are charged using inexpensive late-night power, and this charged power is used as daytime main power or auxiliary power. Has been done.
Electric power companies have power generation capacity that can withstand peak demand, make demand forecasts based on daily weather and temperature forecasts, etc., and supply power by operating power generation facilities and equipment that meet demand . At night when power demand falls, the supply side has thermal power generation facilities that must be operated in order to operate efficiently, and it is cheaper than daytime due to the concept of power load leveling (peak cut / bottom up). Nighttime electricity is supplied at a reasonable price, and nighttime heat storage devices are being popularized.

  A system has been disclosed in which the late-night power set at a low price is stored and discharged at the peak of the daytime to suppress the use of relatively expensive power. (See Patent Documents 1 and 2)

JP H03-226233 A JP 2003-125537 A

However, in a storage battery installed in a power storage system such as Patent Documents 1 and 2, the discharge control performed during the time until the charge start time at night has not been studied. For this reason, when the storage battery completes a predetermined allowable amount of discharge at an early stage from the start of daytime discharge on a day with high power demand, the storage battery is charged from the discharge completion time to the charge start time for charging using midnight power. There was a problem of being left in a discharged state.
When a lead storage battery is used as a storage battery installed in such a power storage system, leaving it in a discharged state is one of the causes that the life of the lead storage battery becomes shorter than the design life. This is not only a power storage system, but also a problem of a lead storage battery for cycle use that repeats deep discharge and charging.
More specifically, when sulfuric acid in the electrolytic solution is consumed by discharge, the specific gravity of the electrolytic solution is lowered and the solubility of metallic lead is increased. If left in such a state for a long time, the lead grid of the positive electrode corrodes. As corrosion progresses, the conductivity of the lead grid decreases and the internal resistance increases, and the expansion capacity of the lead grid causes peeling between the lead grid and the active material, reducing the battery capacity. This will shorten the life of lead-acid batteries.

  As a charge / discharge control method to suppress the shortening of the life of this lead storage battery, it is important to start charging immediately after discharge to suppress the corrosion amount of the lead grid body. In charge / discharge control of a lead-acid battery that has been discharged, the method of verifying that the waiting time from the completion of a predetermined allowable amount of discharge until the start of charging is related to the life of the lead-acid battery is examined, and a method for avoiding adverse effects on the lead-acid battery is studied. It was never done.

An object of the present invention is to extend the life of a lead storage battery in a power storage system in which charge and discharge are performed using the lead storage battery.
Another object of the present invention is to set the above-mentioned charging start time and discharge start time arbitrarily even if the time zone charge of the external power source for charging the lead storage battery varies depending on the season and the power supply status, and relatively A power storage system that can select a time zone during which inexpensive external power is supplied to charge the lead storage battery, and select a time zone during which relatively expensive external power is supplied to discharge the lead storage battery to the load. It is to provide.

Among the present inventions, representative inventions will be described below.
The power storage system according to the present invention includes a lead storage battery, a charging unit that charges the lead storage battery with an external power source, a discharging unit that discharges the lead storage battery to a load, and an SOC detection that detects a state of charge (SOC) of the lead storage battery. And a control means for managing the charging means and the discharging means, and the control means has at least a control function for performing the following operations (1) to (5): .
(1) A function of controlling the discharging means so that the discharge from the lead storage battery to the load becomes a predetermined allowable current value or less when the preset discharge start time t ₁ is reached (2) The SOC detection when the means detects the specified first SOC, from the detection time t _2, the said seek time T _r of the charging to the start time t ₃ when set in advance in order to operate the charging unit, the load from the lead-acid battery discharge, discharge from the time t function of calculating the allowable discharge amount from the difference between the prescribed first 1SOC a small prescribed first 2SOC than that of lead-acid batteries in ₂ (3) detection time t ₂ later until the charging start time t ₃ of the allowable to discharge amount becomes below the regulated current value which is calculated by dividing the time T, function (4) for controlling the discharging means when said leading to charging start time t _3, lead by the discharging means Release of storage battery To start charging the lead-acid battery by the charging means is stopped and when it reaches the function (5) charging end time t ₄ when preset to control said charging means and said discharging means, said by the charging means Function for controlling the charging means to stop the charging of the lead-acid battery and operating the control function of (1) above In the above, setting the external power source for charging the lead-acid battery to a commercial power source supplied from an electric power company Can do. Further, it is preferable that the discharge start time t ₁ , the charge start time t ₃ , the charge end time t ₄ , and the first and second SOCs can be arbitrarily set.

The effects obtained by the representative inventions of the present invention will be briefly described as follows.
According to the present invention, to charge the lead-acid battery using an external power source, and discharged to the load to the provisions of the SOC (State Of Charge), until reaching the charging start time t ₃ from that point, the following adjustment current value By providing the control means for continuing the discharge, corrosion of the grid constituting the electrode plate can be suppressed, so that a long-life power storage system using a lead storage battery can be realized.
Further, when the discharge start time t ₁ , the charge start time t ₃ , the charge end time t ₄ , and the first and second SOCs can be arbitrarily set, the external time depends on the season and the power supply status. Even when the power supply time zone fee fluctuates, electricity is stored by a lead-acid battery that selects a relatively inexpensive electricity fee time zone to store the power and discharges it to the load during the relatively expensive electricity fee time zone A system can be realized.

FIG. 6 is a curve diagram showing the relationship between the standing time from the discharge end time to the charge start time and the corrosion rate of the electrode plate grid in the charge / discharge cycle test of the power storage system using the lead storage battery in the SOC range of 30% to 100%. (The case where the leaving time is 0 is one embodiment of the present invention). It is a simple block diagram of the electrical storage system which is one Embodiment of this invention. It is the flowchart which showed the outline | summary about the example of the control means of the electrical storage system in one Embodiment of this invention. It is the time chart which showed the operation | movement of the electrical storage system which is one Embodiment of this invention. In the charge / discharge cycle test in the SOC range of 30% to 100% of the storage system using the lead storage battery, it is a curve diagram showing the relationship between the standing time from the discharge end time to the charge start time and the number of cycles until the life of the lead storage battery There is one case (one embodiment of the present invention when the standing time is 0).

Hereinafter, an embodiment of a power storage system (power storage system) using a lead storage battery of the present invention will be described with reference to the drawings.
When the lead storage battery is left in a state where the discharge has been completed, corrosion of the lead grid, which is the current collector of the electrode plate, is promoted. In order to confirm this, a storage battery with a nominal voltage of 12 V (6 cells) and a capacity of 50 Ah was prepared, and a charge / discharge cycle test was conducted in the SOC range of 30% to 100%. The corrosion amount of the lead grid of the positive electrode plate was measured according to the length of time. The charge / discharge cycle test conditions are
Discharge: 0.2CA, end DOD 70% (SOC 30%)
Charging: Multistage charging in which the following steps (1) to (4) are performed. (1) Charging to a constant current of 0.2 CA and a voltage value of 2.42 V / cell (2) Constant current of 0.1 CA and a voltage value of 2.42 V (3) Charge to a constant current of 0.05 CA and a voltage value of 2.42 V / cell. (4) Charge at a constant current of 0.02 CA and a voltage value of 2.42 V / cell. A cycle test is performed at the time when the charge reaches 102%, and the cycle test is performed at the end of charging. The remaining time from the discharge end time to the charge start time is set to 0 hr (Example), 1 hr, 2 hr, 3 hr, 4 hr, 6 hr, 8 hr. The results of measuring the lead grid corrosion rate of the positive electrode plate at that time are shown in FIG.
Here, the lead grid corrosion rate of the positive electrode plate was determined by measuring the lead grid corrosion amount of the positive electrode plate after the end of 1000 cycles for each standing time. Regarding the measurement method, first, the storage battery after 1000 cycles is disassembled, and a part of the lead grid is cut out to obtain a measurement sample. Next, it is immersed in a solution for dissolving only the lead lattice corroded layer (3000 g of water mixed with 100 g of sodium hydroxide, 10 g of hydrazine hydrochloride and 20 g of mannitol) to dissolve the corroded layer of the lead lattice. Finally, the amount of corrosion of the lead lattice was determined by measuring the weight change before and after the dissolution of the lead lattice corrosion layer.
FIG. 1 shows that the amount of corrosion of the electrode plate lattice per unit cycle increases as the standing time increases. In particular, the amount of corrosion suddenly increases when the standing time exceeds 4 hours. From this result, it is possible to suppress the corrosion of the electrode plate lattice by shortening the standing time after the discharge, and to suppress the progress of the deterioration of the lead storage battery, thereby extending the life.

  FIG. 2 is a simplified block diagram of a lead storage battery power storage system. The power storage system using a lead storage battery is connected as an auxiliary power source between the external power source 1 and the load facility 3, and charging / discharging is controlled by a control device 5 controlled by a microcomputer (not shown). The SOC of the lead storage battery 7 is detected by the current detector 6 for SOC management during the charge / discharge, and is integrated and managed by the control device 5.

  The charge / discharge control is performed by the control device 5 controlled by a microcomputer (not shown) according to the flowchart shown in FIG. In the computer program for controlling the control device 5, when the lead storage battery 7 waiting in the fully charged state reaches the discharge start set time (S10), the discharge from the lead storage battery to the load is less than a predetermined allowable current value. The discharge means is controlled, and normal discharge is started with respect to the load facility 7 (S20). The predetermined allowable current value may be set to 3 CA or less so that the life of the lead storage battery is not shortened by the large current discharge. In this example, the allowable current value is set to 0.4 CA to suppress the heat generation of the lead storage battery, and the occurrence of early deterioration of the lead storage battery 7, deformation of the battery case, dropping of the terminal, and the like is prevented. The normal discharge is a constant current discharge to the load facility 3 or a constant ratio with respect to the power demand of the load facility 3 or the like. , Can be set and operated arbitrarily. In this example, it is set to supply a part of the power demand of the load facility 3.

In S40, and the SOC of the current time t _n the time of the lead-acid battery, to determine the magnitude of the prescribed first 1SOC set in pre-production, when the SOC of the lead-acid battery of t _n point in time is greater than the prescribed first 1SOC is, the lead-acid battery since the discharge capacity can afford, to determine whether the charging start time t ₃ whether the t _n previously set in S30, t _n performs discharge continuously if the charging start time t ₃ before the charge if the start time t ₃ to end the discharge. When SOC of the lead storage battery of t _n time is equal to or less than the prescribed first 1SOC calculates an adjustment current I _a at S50, is continued until the charging start time t ₃ when preset by adjusting the current value I _a following current To discharge.
Adjustment current I _a are defined first and 1SOC therewith and from the preset small value defining the remaining capacity difference between the lead-acid battery of the first 2SOC C _r (Ah), charging and detection time t ₂ that has detected the prescribed first 1SOC the difference between the starting time t ₃ as T _r (h), the adjustment current I _a is calculated by equation (1), a discharge adjustment current I _a following current continues until the charging start time t ₃ Done. Here, the remaining capacity C _r is obtained by resetting the SOC value in the microcomputer that controls the control device 5 to 100% at the time of starting discharging, and the current detected by the current detector 6 is controlled by the control device 5. It is calculated by the difference with the discharge amount integrated in step (b).
I _a = C _r / T _r Formula (1)
In S60, and the discharge continues until the charging start time t ₃ to the load equipment 3 at the calculated adjusted current value I _a following current S50, when reached the charging start time t _3, and the discharge end, start charging (S80).

An example of a specific implementation will be described with reference to the time chart of FIG. 4. The discharge start time t ₁ is 7:00, the charge start time t ₃ is 23:00, the charge end time t ₄ is 7:00, the specified first SOC is 35%, Lead acid battery that is operated in the range of 30 to 100% SOC, where the specified second SOC is set to 30%, the lead acid battery is charged using cheap nighttime electric power, and is discharged to the load equipment during the daytime power demand The electricity storage system by The charge / discharge control method starts discharging at 7 o'clock. For example, when the specified first SOC is 35% at 18 o'clock, the difference from the specified second SOC is 5%, so if the lead storage battery capacity is C (Ah), C _{Since r} = 0.05C (Ah), and the time T _r = 5 (h) until the charging start time, the adjustment current value I _a (A) is obtained as follows using the equation (1).
_Ia = Cr / _Tr = 0.05C (Ah) / 5 (h) = 0.01C (A) (Formula 1)
In this case, 18:00 reached the first 1SOC exit normal discharge, from 18 am to charging start time 23 continuously discharged at regulated current value I _a, after the discharge due to the following adjustment current value I _a, the lead-acid battery discharge Charging can be started immediately without leaving it in the state.
The discharge starting time t ₁ may be the same as the charging end time t _4, it may be a time later than the charging end time t _4. A discharge start time t ₁ is a time later than the end of charging time t _4, during which time, even without discharge is carried out, lead-acid batteries will not be proceed deterioration because it is in the state of charge.

In FIG. 5, the life of the lead storage battery calculated from the electrode plate corrosion rate when the standing time from the discharge end time to the charging start time is changed is relative to the case where the standing time is 0 (Example) as 100%. Indicate.
From FIG. 5, the life of the lead-acid battery is shortened as the standing time after discharge becomes longer. By implementing this example, charging can be started without leaving the lead storage battery after discharging, so that deterioration of the lead storage battery can be suppressed and a long-life power storage system using the lead storage battery can be realized.

  INDUSTRIAL APPLICABILITY The present invention can be used as a power storage system that uses a cycle, such as a backup power supply application and a power load leveling application.

DESCRIPTION OF SYMBOLS 1 External power supply 2 High voltage load switch 3 Load equipment 4 Inverter 5 Control device 6 Current detector 7 Lead acid battery

Claims (3)

Lead storage battery, charging means for charging the lead storage battery with an external power source, discharging means for discharging from the lead storage battery to the load, SOC detecting means for detecting the state of charge (SOC) of the lead storage battery, and the charging means and discharging A power storage system comprising control means for managing the means, wherein the control means has at least a control function for performing the following operations (1) to (5).
(1) A function of controlling the discharging means so that the discharge from the lead storage battery to the load is less than or equal to a predetermined allowable current value when the preset discharge start time t ₁ is reached. (2) The SOC detecting means. when There detecting a prescribed first SOC, the the detection time t _2, the said seek time T _r until the charging start time t ₃ when set in advance in order to operate the charging unit, to the load from the lead-acid battery discharge, discharge from the time t function of calculating the allowable discharge amount from the difference between the prescribed first 1SOC a small prescribed first 2SOC than that of lead-acid batteries in ₂ (3) detection time t ₂ later until the charging start time t _3, the allowable discharge amount so as to be less than the adjusted current value calculated by dividing the time Tr, function (4) for controlling the discharging means when said leading to charging start time t _3, the by the discharging means lead Electricity storage Of stops the discharge, to start charging of the lead-acid battery by the charging means, when reached to the function (5) charging end time t ₄ when preset to control said charging means and said discharging means, wherein A function of controlling the charging means so as to stop the charging of the lead storage battery by the charging means and operating the control function of (1) above The external power source is a commercial power source supplied from the electric power company, according to claim 1, characterized in that the charging start time t ₃ is set to a time period relatively inexpensive power rate is applied Lead-acid battery power storage system. The prescribed first, the value of the 2SOC, and the discharge starting time t _1, claim 2, wherein a charging start time t _3, characterized in that the charging end time t ₄ can be set arbitrarily The lead acid battery electrical storage system in any one.

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