JP2016119728A - Storage battery charge/discharge control device and storage battery charge/discharge control method - Google Patents

Abstract

Even when a fluctuation in PV power and a fluctuation in load power occur suddenly, it is possible to suppress a sudden increase and instantaneous change in the charge / discharge current value of a storage battery (11), and A storage battery charge / discharge control device (14) and a storage battery charge / discharge control method that achieve deterioration prevention and long life are obtained.
The storage battery is charged / discharged at a charge / discharge current value calculated based on the charging / discharging time, the PV power generated in the PV system (20), the load power consumed by the load (40), and the storage battery state of the storage battery. .
[Selection] Figure 1

Description

  The present invention relates to a charge / discharge control device for a storage battery and a charge / discharge control method for the storage battery that control the charge / discharge of the storage battery in the storage battery system to prevent deterioration of the storage battery and extend its life.

  In recent years, smart houses that can reduce carbon dioxide emissions by controlling energy equipment such as photovoltaic power generation (hereinafter referred to as PV) systems, home appliances, and housing equipment, and performing energy management. Proposed.

  In such a smart house, a storage battery (stationary type) is used in order to effectively use surplus power of the PV power generated by the PV system and midnight power supplied from a commercial power source at a low price. Storage battery) is installed. Moreover, such a storage battery also serves as an emergency power source during a power failure.

  Here, when charging / discharging of a storage battery is performed according to the fluctuation | variation of PV electric power and the fluctuation | variation of load electric power, conventionally, in order to aim at prevention of deterioration of a storage battery and prolonging life, various charging / discharging of a storage battery is controlled. There is a way.

  As one of such methods, when the discharge current value of the storage battery reaches a preset value, there is a method of separating the storage battery and the load and suppressing the discharge current of the storage battery from becoming too large ( For example, see Patent Document 1).

  In addition, since PV power tends to fluctuate and is unstable in nature, when charging PV power to a storage battery, the charging current of the storage battery tends to fluctuate. Therefore, in order to suppress the fluctuation of the charging current, there is a method of charging the storage battery with a constant charging current while adjusting the charging current corresponding to the fluctuation with the grid current from a general grid power supply (commercial power supply) (for example, Patent Document 2).

  In addition, when charging a storage battery from a commercial power source at midnight hours when the electricity rate is low, the storage battery is fully charged by delaying the charging start time so that the storage battery should not be fully charged. There is a method of reducing time (hereinafter, referred to as full charge maintenance time) (see, for example, Patent Document 3). Similarly, when charging a storage battery at midnight, the first charge amount and the second charge amount are set as the charge amount of the storage battery, and the full charge maintenance time of the storage battery is reduced by performing two-stage charging. (For example, refer patent document 4).

International Publication No. 2012/049972 Pamphlet JP-A-62-89435 JP 2010-259163 A JP 2012-39725 A

However, the prior art has the following problems.
In the prior art described in Patent Literatures 1 to 4, the charging current value of the storage battery is not controlled (cannot be set), and can take various current values depending on the fluctuation of PV power and the fluctuation of load power. There is no change. Therefore, if the fluctuation of the PV power and the fluctuation of the load power occur suddenly, the charge / discharge current value of the storage battery suddenly increases or the charge / discharge current value of the storage battery changes instantaneously. In such a case, as a result, there is a problem that the storage battery may be deteriorated or the life may be shortened.

  The present invention has been made to solve the above-described problems, and even when fluctuations in PV power and load power occur suddenly, the charge / discharge current value of the storage battery rapidly increases. An object of the present invention is to obtain a storage battery charge / discharge control device and a storage battery charge / discharge control method that can suppress the instantaneous change and prevent the deterioration of the storage battery and extend its life.

  A storage battery charge / discharge control device according to the present invention detects PV power generated in a photovoltaic power generation (PV) system, system power supplied from a system power supply, and load power consumed by a load, and is also used for midnight Is a storage battery charge / discharge control device that performs storage battery discharge control during daytime hours defined as a time zone other than midnight time zone. The charging current value is calculated by calculating the charging rate so that the amount of increase in the charging rate per unit time until the charging rate of the storage battery reaches the desired upper limit SOC value by the desired charging end time is constant. The storage battery is charged until the charging rate reaches the upper limit SOC value at the set charging current value. In the daytime period, if the current PV power is less than or equal to the current load power, the current time By calculating the first discharge rate so that the amount of decrease per unit time of the charge rate until the charge rate of the storage battery reaches the desired lower limit SOC value by the desired discharge end time, the first discharge is calculated. The first storage battery output obtained by setting the current value and multiplying the set first discharge current value by the storage battery voltage is obtained by subtracting the current PV power from the current load power. When the difference is smaller than one difference value, the storage battery is discharged until the charging rate reaches the lower limit SOC value at the set first discharge current value.

  The storage battery charge / discharge control method according to the present invention includes a step of detecting PV power generated in a photovoltaic power generation (PV) system, system power supplied from a system power source, and load power consumed by the load; In the midnight hours, the charging rate is such that the amount of increase in the charging rate per unit time until the charging rate of the storage battery reaches the desired upper limit SOC value from the desired charging start time to the desired charging end time is constant. By setting the charging current value, charging the storage battery until the charging rate reaches the upper limit SOC value at the set charging current value, and the daytime specified as a time zone other than the midnight time zone In the band, when the current PV power is less than or equal to the current load power, the charging rate until the charging rate of the storage battery reaches the desired lower limit SOC value from the current time to the desired discharge end time It is obtained by setting the first discharge current value by calculating the first discharge rate so that the amount of decrease per unit time is constant, and multiplying the set first discharge current value by the storage battery voltage. When the first storage battery output of the storage battery is smaller than the first difference value obtained by subtracting the current PV power from the current load power, the charging rate reaches the lower limit SOC value at the set first discharge current value. And discharging the storage battery until it is done.

  According to the present invention, the storage battery is charged / discharged with the charge / discharge current value calculated based on the charge / discharge time, the PV power, the load power, and the storage battery state. As a result, even when PV power fluctuations and load power fluctuations occur suddenly, it is possible to suppress rapid increases and instantaneous changes in the charge / discharge current value of the storage battery, and to prevent deterioration of the storage battery and It is possible to obtain a storage battery charge / discharge control device and a storage battery charge / discharge control method that achieve a long life.

It is a block diagram of the system | strain connection system in Embodiment 1 of this invention. It is the flowchart explaining the charging / discharging control of the storage battery by the charging / discharging control apparatus in Embodiment 1 of this invention. In Embodiment 1 of this invention, it is explanatory drawing which showed the change of the charging rate when charge control of a storage battery is performed in the midnight time zone. In Embodiment 1 of this invention, it is explanatory drawing which showed the change of PV electric power and load electric power when PV electric power falls below load electric power during the daytime. In Embodiment 1 of this invention, when PV electric power falls below load electric power in the daytime, it is explanatory drawing which showed the change of the charging rate when discharge control of a storage battery is performed. In Embodiment 1 of this invention, it is explanatory drawing which showed the change of PV electric power and load electric power when PV electric power exceeds load electric power around noon in the daytime. In Embodiment 1 of this invention, it is explanatory drawing which showed an example of the change of a charging rate when discharge control of a storage battery is performed when PV electric power exceeds load electric power around noon in the daytime. In Embodiment 1 of this invention, it is explanatory drawing which showed another example of the change of a charging rate when discharge control of a storage battery is performed when PV electric power exceeds load electric power around noon in the daytime. . In Embodiment 1 of this invention, it is explanatory drawing which showed the change of PV electric power and load electric power when PV electric power exceeds load electric power from the morning to the evening in the daytime. In Embodiment 1 of this invention, it is explanatory drawing which showed the change of the charging rate when discharge control of a storage battery is performed when PV electric power exceeds load electric power in the daytime from morning to noon. . It is explanatory drawing which showed the change of the capacity maintenance rate of the storage battery in Embodiment 1 of this invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, a storage battery charge / discharge control device and a storage battery charge / discharge control method according to the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same reference numerals are assigned to the same elements, and duplicate descriptions are omitted.

Embodiment 1 FIG.
FIG. 1 is a configuration diagram of a system linkage system according to Embodiment 1 of the present invention. The system linkage system in FIG. 1 includes a storage battery system 10, a PV system 20, a CT sensor 30, a load 40, and a system power supply 50.

  The storage battery system 10 includes a storage battery 11, a battery management unit (hereinafter referred to as BMU) 12, a storage battery power conditioner (hereinafter referred to as storage battery PCS) 13, and a charge / discharge control device (hereinafter referred to as charge / discharge control device) of the storage battery 11. (Referred to as a discharge control device) 14. The PV system 20 includes a PV device 21 and a PV power conditioner (hereinafter referred to as a PV PCS) 22.

  The storage battery 11 in the storage battery system 10 charges the supplied power and discharges the power stored by charging. The BMU 12 connected to the storage battery 11 has a protection function and a state monitoring function for safety management of the storage battery 11, and acquires information on the storage battery 11 based on these functions. Specifically, if overcharge, overdischarge, overvoltage, overcurrent, temperature abnormality, or the like occurs in the storage battery 11, the BMU 12 pauses the operation (charge / discharge) of the storage battery 11 with a protection function. Further, the BMU 12 monitors the storage battery state such as voltage measurement, current measurement, electric energy measurement, charge / discharge end management, and remaining capacity management in the storage battery 11 by the state monitoring function.

  The storage battery PCS 13 connected to the BMU 12 converts AC power obtained by converting PV power from a PV device 21 in the PV system 20 described later into AC and AC power from the system power supply 50 into DC power, and passes through the BMU 12. And supplied to the storage battery 11. Further, the storage battery PCS 13 acquires information on the PV power and the load power detected by the CT sensor 30.

  The charge / discharge control device 14 acquires information on the storage battery state, PV power, and load power of the storage battery 11 from the BMU 12 and the storage battery PCS 13, and performs charge / discharge control of the storage battery 11. Specifically, the charge / discharge control device 14 controls the operation state of the storage battery 11 to any one of the discharge mode, the charge mode, and the hibernation mode based on the acquired information, and the charge / discharge of the storage battery 11. Determine the current value.

  The PV device 21 in the PV system 20 generates PV power from sunlight. The PV PCS 22 converts the PV power generated by the PV device 21 into alternating current, and supplies the converted alternating current power to the storage battery PCS 13 and the load 40 to be connected. The CT sensor 30 detects the PV power generated by the PV device 21 and the load power consumed by the load 40.

  The load 40 consumes AC power supplied from the storage battery PCS 13, the PV PCS 22, and the system power supply 50 as load power. The system power supply 50 is, for example, a single-phase or three-phase commercial power supply.

  Next, charge / discharge control of the storage battery 11 by the charge / discharge control device 14 will be described with reference to the flowchart of FIG. FIG. 2 is a flowchart illustrating charge / discharge control of storage battery 11 by charge / discharge control device 14 according to Embodiment 1 of the present invention.

  First, in step S <b> 101, the charge / discharge control device 14 determines whether or not the current time (current time) is a time zone of midnight power with an inexpensive electricity bill. In the following description, a time zone of late-night power with a low electricity charge is simply referred to as a midnight time zone.

  In step S101, when the charge / discharge control device 14 determines that the current time is not a midnight time zone (that is, NO), the process proceeds to step S201 described later. That is, the daytime time zone in which the current time is defined as a time zone other than the midnight time zone (here, the time zone from 8:00 to 23:00 is defined as the daytime zone, and from 23:00 to 8:00 the next morning) Is defined as a midnight time zone), it is determined that it is not a midnight time zone. On the other hand, if it is determined in step S101 that the current time is the midnight time zone (that is, YES), the process proceeds to step S102.

  In step S <b> 102, the charge / discharge control device 14 sets an upper limit SOC (State Of Charge) of the storage battery 11. In addition, the upper limit SOC of the storage battery 11 should just set the desired upper limit SOC previously by the user. Next, in step S <b> 103, the charge / discharge control device 14 sets a charging end time at which charging of the storage battery 11 ends. The charging end time is set such that, for example, charging of the storage battery 11 ends at 8:00, which is the end time of the midnight time zone.

  In step S104, the charge / discharge control device 14 calculates a charge rate based on the upper limit SOC set in step S102 and the charge end time set in step S103, and sets a charge current value. That is, the charging current value is set so that the amount of increase in the charging rate per unit time until the charging rate of the storage battery 11 reaches the upper limit SOC value from the current SOC value becomes constant by the end of charging time in the midnight time zone. Will be set. Specifically, the charging rate is calculated and the charging current value is set according to the following equation (1).

  The charging rate indicates a relative ratio of current during charging to the capacity of the storage battery 11, and the unit is represented by C. For example, the charging rate of 1 C is a current value that completes charging in 1 hour (reach the upper limit SOC) when the storage battery 11 having the nominal capacity is charged with constant current, and the charging rate is 0. .2C is a current value at which charging is completed in 5 hours (up to the upper limit SOC).

  In the first embodiment, the charging start time is exemplified by setting at 23:00, which is the start time of the midnight time zone, but is not limited thereto, and may be another time in the midnight time zone. Further, for example, when the charge start time is set to 2 o'clock after 24:00 and the charge rate is calculated according to the above equation (1), the current time is calculated as 26:00 instead of 2 o'clock. In the first embodiment, the charging end time is exemplified by setting it to 8:00, which is the end time of the midnight time zone, but is not limited thereto, and may be another time in the midnight time zone.

  Next, in step S <b> 105, the charge / discharge control device 14 starts charging the storage battery 11 using the grid power from the grid power supply 50 according to the charge current value set at the charge rate calculated in step S <b> 104.

  Next, in step S106, the charge / discharge control device 14 determines whether or not the charging rate of the storage battery 11 has reached the upper limit SOC. That is, it is determined whether or not the current time is the charging end time at which the charging rate of the storage battery 11 reaches the upper limit SOC.

  In step S106, when it is determined that the charging rate of the storage battery 11 has not reached the upper limit SOC (that is, NO), the charge / discharge control device 14 returns to step S105 and continues charging the storage battery 11. On the other hand, when the charge / discharge control device 14 determines in step S106 that the charging rate of the storage battery 11 has reached the upper limit SOC (that is, YES), the process of the flowchart of FIG.

  For example, if the charging end time is set to 8:00 by a series of execution processes of step S101 to step S106, the charging rate of the storage battery 11 is set to the upper limit SOC at the time of 8:00, which is the end time of the midnight time zone. Reached for the first time.

  Here, if the current time is the daytime time zone from 8:00 to 23:00, the charging / discharging control device 14 determines in step S101 that the current time is not a midnight time zone (that is, NO). The process proceeds to step S201.

  In step S201, the charge / discharge control device 14 determines whether the PV power detected by the CT sensor 30 is larger than the load power. In step S201, when the charge / discharge control device 14 determines that the PV power is larger than the load power (that is, YES), the process proceeds to step S202. Here, when the PV power is larger than the load power, the load 40 is operated using the system power from the system power supply 50 and the PV power from the PV device 21.

  In step S <b> 202, the charge / discharge control device 14 determines whether to charge the storage battery 11. Specifically, for example, if the current charging rate of the storage battery 11 is not the upper limit SOC, it is determined to charge the storage battery 11, and if it is the upper limit SOC, it is determined not to charge the storage battery 11.

  In step S202, when the charge / discharge control device 14 determines to charge the storage battery 11, in step S203, the operation state of the storage battery 11 is set to the charging mode, and surplus power in the PV power is supplied to the storage battery 11. The storage battery 11 is charged. On the other hand, when it is determined in step S202 that the storage battery 11 is not charged, in step S204, the charging / discharging of the storage battery 11 is paused by setting the operation state of the storage battery 11 to the sleep mode (charging / discharging). Do not).

  Moreover, after performing the process of step S203 or step S204, the charging / discharging control apparatus 14 returns to step S201, and performs the process after step S201. In step S <b> 203 and step S <b> 204, the charge / discharge control device 14 may sell surplus power in the PV power via the system power supply 50.

  On the other hand, in step S201, when the charge / discharge control device 14 determines that the PV power is equal to or lower than the load power (that is, NO), the process proceeds to step S205.

  In step S205, the charge / discharge control device 14 sets the desired lower limit SOC of the storage battery 11, sets the desired discharge end time at which the discharge of the storage battery 11 ends, and sets the lower limit SOC and the discharge end, as before. Based on the time, the discharge rate is calculated and the discharge current value is set.

  That is, the discharge current value so that the amount of decrease in the charging rate per unit time until the charging rate of the storage battery 11 reaches the lower limit SOC value from the current SOC value becomes constant by the discharge end time in the daytime period. Will be set. Specifically, the discharge rate is calculated according to the following formula (2), and the discharge current value is set.

  The discharge rate indicates a relative ratio of the current during discharge to the capacity of the storage battery 11, and the unit is represented by C. For example, the charge rate of 1 C is a current value at which discharge is completed in 1 hour (reaching the lower limit SOC) when the storage battery 11 having a nominal capacity is discharged at a constant current, and the charge rate is 0. .2C is a current value at which discharge is completed in 5 hours (lower limit SOC is reached).

  Next, in step S206, the charge / discharge control device 14 calculates the storage battery output (discharge power) of the storage battery 11 according to the discharge current value set at the discharge rate calculated in step S205. Specifically, the product of the current charging voltage value of the storage battery 11 and the set discharge current value is calculated as the current storage battery output.

  Next, in step S207, the charge / discharge control device 14 obtains the first difference value (= load power−PV power) obtained by subtracting the current PV power from the current load power from the storage battery output calculated in step S206. Or less. That is, the charge / discharge control device 14 compares the magnitudes of the storage battery output and the first difference value based on the monitoring results of the detected values of the PV power and the load power detected by the CT sensor 30.

  In step S207, when the charge / discharge control device 14 determines that the storage battery output is greater than or equal to the first difference value (that is, NO), the charge / discharge control device 14 returns to step S204 and sets the operation state of the storage battery 11 to the sleep mode. 11 charge / discharge (operation) is paused (leaves pause). In this case, the load 40 is operated using the system power from the system power supply 50 and the PV power from the PV device 21.

  Here, the PV power is unstable because the power value is likely to change rapidly depending on the weather. Therefore, when discharging the storage battery 11 having a storage battery output equal to or greater than the first difference value to supply power to the load 40, for example, when a sudden change in PV power occurs, to compensate for the change In addition, the power supplied to the load 40 may increase. In such a case, the discharge current of the storage battery 11 increases rapidly, and as a result, the storage battery may be deteriorated. Therefore, when the storage battery output is greater than or equal to the first difference value, charging / discharging of the storage battery 11 is suspended and the load 40 is operated with system power and PV power so as not to generate extra power from the storage battery 11. Thereby, it does not receive to the influence of the rapid fluctuation | variation of PV electric power and load electric power.

  On the other hand, in step S207, when the charge / discharge control device 14 determines that the storage battery output is smaller than the first difference value (that is, YES), in step S208, according to the set discharge current value, the storage battery 11 Start discharging.

  In this case, the load 40 is operated using the system power from the system power supply 50, the PV power from the PV device 21, and the discharge power from the storage battery 11. Moreover, about the storage battery 11, according to the set discharge current value, the system power from the system power supply 50 is made to follow the fluctuation of the PV power and the load power so that the battery 11 can be discharged while maintaining a constant current value. .

  Here, the household load can be efficiently operated by discharging the storage battery 11 having a storage battery output smaller than the first difference value.

  Next, in step S209, the charge / discharge control device 14 determines whether or not the charging rate of the storage battery 11 has reached the lower limit SOC. In step S209, when it is determined that the charging rate of the storage battery 11 has not reached the lower limit SOC (that is, NO), the charge / discharge control device 14 returns to step S207, and the storage battery output is again the first difference. It will be determined whether it is smaller than the value. That is, the calculation in step S207 is repeatedly performed. Here, if it is determined in step S207 that the storage battery output is smaller than the first difference value, in step S208, the storage battery 11 is continuously discharged at the set discharge current value.

  On the other hand, when the charge / discharge control device 14 determines in step S209 that the charging rate of the storage battery 11 has reached the lower limit SOC, the process of the flowchart of FIG.

  For example, if the discharge end time is set to 23:00 by a series of execution processes of step S201 to step S209, the charging rate of the storage battery 11 is set to the lower limit at the time of 23:00, which is the end time of the daytime period. The SOC is reached for the first time.

  In the first embodiment, the discharge start time is set to 8 o'clock, which is the start time of the daytime period, but is not limited thereto, and may be another time of the daytime period. In the first embodiment, the discharge end time is set to 23:00, which is the end time of the daytime time zone, but is not limited to this, and may be another time of the daytime time zone. Also, for example, when the discharge end time is set to 2 o'clock after 24:00 and the discharge rate is calculated according to the above equation (2), the discharge end time is calculated as 26:00 instead of 2 o'clock.

  Next, an example of a simulation test of charge / discharge control of the storage battery 11 by the charge / discharge control device 14 will be described with reference to FIGS. FIG. 3 is an explanatory diagram showing a change in the charging rate when the charging control of the storage battery 11 is performed in the midnight time zone in the first embodiment of the present invention. FIG. 4 is an explanatory diagram showing changes in PV power and load power when PV power falls below load power over the daytime in Embodiment 1 of the present invention. FIG. 5 is an explanatory diagram showing a change in the charging rate when the discharge control of the storage battery 11 is performed when the PV power falls below the load power over the daytime in the first embodiment of the present invention.

  Here, for the sake of specific explanation, it is assumed that the performance of the storage battery 11 is that the nominal capacity is 30 Ah, 6 kW, the upper limit SOC of the storage battery 11 is set to 100%, and the lower limit SOC is set to 25%. . Moreover, the case where the PV panel whose maximum PV electric energy is 3.2 kW is used as the PV apparatus 21 in the PV system 20 is assumed.

  First, the charge control operation of the storage battery 11 in the midnight time zone by the charge / discharge control device 14 will be described. As shown in FIG. 3, the charging / discharging control device 14 controls charging of the storage battery 11 at 23:00 to 8:00, which is a midnight time zone. In this case, as described above, the charge / discharge control device 14 calculates the charge rate and sets the charge current value according to the above equation (1).

  The current time at which charging is started is 23:00, and the charging end time is 8:00. Further, regarding the charging rate of the storage battery 11, the current (23:00) SOC is set to 25%, which is the lower limit SOC, and the SOC at the end of charging is set to 100%, which is the upper limit SOC. Specifically, it is calculated as in the following formula (3).

  As shown in FIG. 3, the charging / discharging control device 14 has a constant increase in the charging rate of the storage battery 11 per unit time in 9 hours from 23:00 to 8:00, as shown in FIG. 3. From 25%, which is the lower limit SOC, to 100%, which is the upper limit SOC (the storage battery 11 is charged to full charge). Therefore, if the current time (charging start time) and the charging end time at which charging is started in the midnight time zone are changed, it is possible to charge to full charge at a desired charging rate. In addition, in the midnight time zone, in particular, when charging is performed so that the charging rate of the storage battery 11 is changed from the lower limit SOC to the upper limit SOC by setting the charging start time to 23:00 and the charging end time to 8:00, the lowest charging current value is used. It will be possible to charge up to full charge.

  Further, the charge / discharge control device 14 changes the setting of the charging current value in accordance with a desired upper limit SOC set in advance. That is, for example, as shown in FIG. 3, if the upper limit SOC is changed to 90%, the charging rate of the storage battery 11 is reduced from 25%, which is the lower limit SOC, to the upper limit SOC in 9 hours from 23:00 to 8:00. The setting of the charging current value is changed to be 90%. In addition, the charging / discharging control apparatus 14 may set a charging current value so that the charging rate of the storage battery 11 becomes the upper limit SOC in a shorter time than 9 hours from 23:00 to 8:00.

  Here, conventionally, unlike the first embodiment, charging is performed at a specified charging current value without setting the charging end time. For example, as shown in FIG. The behavior is such that the charging rate of the storage battery 11 becomes 100% which is the upper limit SOC in 4 hours, and the control of the charging current value (the control of the slope indicating the change in the charging rate) cannot be performed. Therefore, as a result, the full charge maintenance time of the storage battery 11 cannot be controlled, and it has not been possible to prevent the deterioration of the storage battery and extend its life.

  On the other hand, in this Embodiment 1, the full charge maintenance time of the storage battery 11 is controllable by setting a charging current value. Therefore, for example, if the storage battery 11 is charged to the full charge at the lowest charging current value in the midnight time zone, the full charge maintenance time of the storage battery 11 can be reduced to the minimum, and the deterioration of the storage battery can be prevented and the life can be extended. Is possible.

  Next, the discharge control operation of the storage battery 11 in the daytime time zone by the charge / discharge control device 14 will be described.

  For example, since the weather during the day is bad and the PV power is low, a case is assumed in which the PV power changes below the load power during the day as shown in FIG. In this case, as shown in FIG. 5, the charge / discharge control device 14 controls the discharge of the storage battery 11 at 8:00 to 23:00, which is the daytime time zone.

  That is, since the PV power is small, the load 40 is operated using the system power from the system power supply 50, the PV power from the PV device 21, and the discharge power from the storage battery 11. Then, at 8:00, which is the start time of the daytime period, as described above, the discharge rate is calculated and the discharge current value is set according to the above equation (2).

  It is assumed that the current time (discharge start time) at which discharge starts is 8:00 and the discharge end time is 23:00. Further, regarding the storage rate of the storage battery 11, the current (8 o'clock) SOC is 100% which is the upper limit SOC, and the SOC at the end of discharge is 25% which is the lower limit SOC. Specifically, it is calculated as in the following formula (4).

  The charge / discharge control device 14 calculates the storage battery output by multiplying the current storage battery voltage value of the storage battery 11 and the set discharge current value. And when a storage battery output is smaller than the 1st difference value mentioned above, the charging / discharging control apparatus 14 starts discharge of the storage battery 11 according to the set discharge current value.

  Further, when the daytime weather is bad and the PV power changes below the load power during the day as shown in FIG. 4, the storage battery output is always smaller than the first difference value. Therefore, as shown in FIG. 5, the charge / discharge control device 14 has an upper limit SOC of 100 while the reduction rate per unit time of the charging rate of the storage battery 11 becomes constant in 15 hours from 8:00 to 23:00. Storage battery 11 will continue to be discharged at a discharge current value (1.5 A) that is set to 25% that is the lower limit SOC from%. In addition, when the storage battery 11 is continuously discharged at 1.5 A, the power shortage with respect to the load 40 is supplemented with the system power from the system power supply 50.

  Therefore, if the current time (discharge start time) and discharge end time at which the daytime discharge is started are changed, it is possible to discharge to the lower limit SOC at a desired discharge rate. Further, in the daytime period, in particular, when the discharge start time is set to 8 o'clock and the discharge end time is set to 23:00 so that the charge rate of the storage battery 11 is changed from the upper limit SOC to the lower limit SOC, the lowest discharge current value Thus, it is possible to discharge to the lower limit SOC.

  Here, conventionally, unlike the first embodiment, since the storage battery is discharged according to the fluctuation of PV power and the fluctuation of load power without setting the discharge current value, the behavior of the discharge current value is controlled. could not. That is, conventionally, according to fluctuations in PV power and load power, for example, as shown in FIG. 5, the charging rate of the storage battery 11 is reduced to 25%, which is the lower limit SOC, in one hour from 8:00 to 9:00. Therefore, it is impossible to control the discharge current value (control of the slope indicating a change in the charging rate). Therefore, as a result, even when a sudden change in PV power or load power occurs during discharge of the storage battery, the discharge current value may increase unexpectedly, preventing deterioration of the storage battery and extending its life. Could not be realized.

  On the other hand, in this Embodiment 1, the discharge current value of the storage battery 11 can be controlled by setting the discharge current value. Therefore, for example, if the storage battery 11 is discharged to the lower limit SOC at the lowest discharge current value in the daytime period, the discharge current value will not increase unexpectedly, preventing deterioration of the storage battery and extending its life. Is possible.

  Next, the storage battery 11 of the daytime time zone by the charge / discharge control device 14 performed in another case other than the case where the PV power changes below the load power over the daytime (see FIGS. 4 and 5 above). The discharge control operation will be described with reference to FIGS. FIG. 6 is an explanatory diagram showing changes in PV power and load power when PV power exceeds load power around noon in the daytime in Embodiment 1 of the present invention. FIG. 7 shows an example of the change in the charging rate when the discharge control of the storage battery 11 is performed when the PV power exceeds the load power around noon in the daytime in Embodiment 1 of the present invention. It is explanatory drawing. FIG. 8 shows another example of the change in the charging rate when the discharge control of the storage battery 11 is performed when the PV power exceeds the load power around noon in the daytime in Embodiment 1 of the present invention. FIG.

  Here, for example, it is assumed that the daytime is cloudy in the morning and the weather is sunny around noon, and as shown in FIG. 6, the PV power changes above the load power around noon in the daytime. To do. In this case, the charge / discharge control device 14 controls the discharge of the storage battery 11 as shown in FIG. 7 when the storage battery 11 is not charged with surplus power of the PV power. On the other hand, the charging / discharging control device 14 performs discharge control of the storage battery 11 as shown in FIG.

  First, the case where the charge / discharge control device 14 controls the discharge of the storage battery 11 as shown in FIG. 7 will be described. In this case, since the PV power is lower than the load power in the morning, the system power from the system power supply 50, the PV power from the PV device 21 and the discharge power from the storage battery 11 are used as in FIG. The load 40 is operated. Then, at the time of 8 o'clock, the discharge rate is calculated and the discharge current value is set according to the above equation (2), as in FIG.

  At 8 o'clock, the current time at which discharge starts (discharge start time) is 8 o'clock, the discharge end time is 23:00, and the current (8 o'clock) SOC is the upper limit SOC of 100%. Assuming that the SOC at the end of the discharge is 25%, which is the lower limit SOC, the discharge rate is calculated and the discharge current value is set. Specifically, it is calculated as in the following formula (5).

  The charge / discharge control device 14 calculates the storage battery output by multiplying the current storage battery voltage value of the storage battery 11 and the set discharge current value. When the storage battery output is smaller than the first difference value, the charge / discharge control device 14 starts discharging the storage battery 11 according to the set discharge current value as described above.

  Here, as shown in FIG. 6, the PV power increases after 10 o'clock, and when the storage battery output is equal to or greater than the first difference value, the charge / discharge control device 14 is as described above. Then, the discharge of the storage battery 11 is stopped. In this case, the load 40 is operated using the system power from the system power supply 50 and the PV power from the PV device 21.

  Also, as shown in FIG. 6, at 13:00, PV power is less than load power in the morning. In such a case, the discharge rate is calculated again according to the above equation (2), and the discharge current value is reset.

  At 13:00, the current start time (discharge start time) is 13:00, the discharge end time is 23:00, and the current (13:00) SOC is 90%. The SOC at that time is set to 25% which is the lower limit SOC, the discharge rate is calculated again, and the discharge current value is reset. Moreover, since the charging / discharging control apparatus 14 is discharging the storage battery 11, the charging rate of the storage battery is reduced from 100% which is the upper limit SOC to 90%. Specifically, it is calculated as in the following formula (6).

  The charge / discharge control device 14 calculates the storage battery output by multiplying the current storage battery voltage value of the storage battery 11 and the reset discharge current value. And when a storage battery output is smaller than a 1st difference value, the charging / discharging control apparatus 14 starts the discharge of the storage battery 11 again according to the reset current value reset as mentioned above. Then, as shown in FIG. 7, in 10 hours from 13:00 to 23:00, the charging rate of the storage battery 11 is reset so that the amount of decrease per unit time becomes constant and the lower limit SOC is 25%. The storage battery 11 will continue to be discharged at the discharge current value (1.95 A).

  In summary, as shown in FIG. 7, the charge / discharge control device 14 discharges the storage battery 11 at the set discharge current value (1.5 A) from 8 o'clock to 10 o'clock in the daytime period. Since it continues, the charging rate of the storage battery 11 falls from 100% which is upper limit SOC. Moreover, since the charging / discharging control apparatus 14 stops discharge of the storage battery 11 from about 10:00 to 13:00, it will be in the state by which the charging rate of the storage battery 11 was maintained constant. Furthermore, from 13:00 to 23:00, the storage battery 11 continues to be discharged again with the reset discharge current value (1.95) A, so the charge rate of the storage battery 11 is reduced to 25%, which is the lower limit SOC.

  Here, conventionally, unlike the first embodiment, since the storage battery is discharged according to the fluctuation of PV power and the fluctuation of load power without setting the discharge current value, the behavior of the discharge current value is controlled. could not. That is, conventionally, according to the fluctuation of PV power and the fluctuation of load power, for example, as shown in FIG. 7, the charging rate of the storage battery 11 becomes 80% in 2 hours from 8 o'clock to 10 o'clock. It is in a state where it remains constant at 80% in 3 hours from 13:00 to 13:00, and exhibits a behavior such that the lower limit SOC is 25% in 6 hours from 13:00 to 19:00. (Slope control showing change in charging rate) is not possible. On the other hand, in the first embodiment, even if the PV power fluctuates greatly during the daytime, the discharge current value of the storage battery 11 can be controlled, so that the same effect as described above can be obtained.

  Next, the case where the charge / discharge control device 14 controls the discharge of the storage battery 11 as shown in FIG. 8 will be described. In this case, as in FIG. 7, from 8 o'clock to 10 o'clock, which is the start time of the daytime time zone, the storage battery 11 is continuously discharged at the set discharge current value (1.5 A). The charging rate decreases from 100%, which is the upper limit SOC.

  Also, as shown in FIG. 6, PV power increases after 10 o'clock, and when the storage battery output is equal to or greater than the first difference value, the charge / discharge control device 14, as described above, Discharging the storage battery 11 is suspended. In this case, the load 40 is operated using the system power from the system power supply 50 and the PV power from the PV device 21, and the surplus power in the PV power is charged to the storage battery 11, so that FIG. As shown, the charging rate of the storage battery 11 becomes 100%, which is the upper limit SOC again.

  Also, as shown in FIG. 6, at 13:00, the PV power is less than the load power as in the morning. In such a case, the discharge rate is calculated again according to the above equation (2), and the discharge current value is reset.

  At 13:00, the current time (discharge start time) at which discharge starts is 13:00, the discharge end time is 23:00, and the current (13:00) SOC is 100%. The SOC at that time is set to 25% which is the lower limit SOC, the discharge rate is calculated again, and the discharge current value is reset. Specifically, it is calculated as in the following formula (7).

  Similarly, as shown in FIG. 8, the charge / discharge control device 14 has a constant decrease in the charging rate of the storage battery 11 per unit time in 10 hours from 13:00 to 23:00, and the lower limit SOC. Thus, the storage battery 11 is continuously discharged at the discharge current value (2.25 A) reset to be 25%.

  In summary, as shown in FIG. 8, the charge / discharge control device 14 discharges the storage battery 11 at the set discharge current value (1.5 A) from 8:00 to 10:00 in the daytime period. Since it continues, the charging rate of the storage battery 11 falls from 100% which is upper limit SOC. Moreover, since the charging / discharging control apparatus 14 stops charging from about 10:00 to 13:00 and performs charging, the charging rate of the storage battery 11 becomes constant after reaching the upper limit SOC of 100%. It will be maintained. Furthermore, from 13:00 to 23:00, the storage battery 11 continues to be discharged again with the reset discharge current value (2.25) A, so the charge rate of the storage battery 11 is reduced to 25%, which is the lower limit SOC.

  Here, conventionally, unlike the first embodiment, since the storage battery is discharged according to the fluctuation of PV power and the fluctuation of load power without setting the discharge current value, the behavior of the discharge current value is controlled. could not. That is, conventionally, according to the fluctuation of the PV power and the fluctuation of the load power, for example, as shown in FIG. 8, the charging rate of the storage battery 11 becomes 80% in 2 hours from 8 o'clock to 10 o'clock. It becomes 100% which is the upper limit SOC in 3 hours from -13: 00 and remains constant at 100%, and it becomes 25% which is the lower limit SOC in 8 hours from 13:00 to 21:00. It shows behavior and cannot control the discharge current value (control of the slope indicating the change in the charging rate). On the other hand, in the first embodiment, the discharge current value of the storage battery 11 can be controlled even if the PV power fluctuates greatly during the daytime period, so that a desired discharge rate corresponding to the current time is obtained. Finally, the battery can be discharged to the lower limit SOC.

  Next, a charge / discharge control device performed in another case other than the case where the PV power exceeds the load power and the PV power and the load power change around noon (see FIGS. 6 to 8). 14, the discharge control operation of the storage battery 11 in the daytime time zone will be described with reference to FIG. 9 and FIG. FIG. 9 is an explanatory diagram showing changes in PV power and load power when the PV power exceeds the load power from morning to evening in the daytime in Embodiment 1 of the present invention. FIG. 10 shows a change in the charging rate when the discharge control of the storage battery 11 is performed when the PV power exceeds the load power from morning to evening in the daytime in Embodiment 1 of the present invention. FIG.

  Here, for example, it is assumed that the PV power changes more than the load power from morning to evening in the daytime as shown in FIG. In this case, as shown in FIG. 10, the charge / discharge control device 14 controls the discharge of the storage battery 11.

  That is, in the morning of the daytime hours, the PV power is larger than the load power, so the load 40 is operated using the system power from the system power supply 50 and the PV power from the PV device 21.

  Therefore, the charging / discharging control device 14 pauses the discharge of the storage battery 11 (does not discharge), so that the charge rate of the storage battery 11 remains constant at the upper limit SOC of 100%. Normally, since the charging rate of the storage battery 11 is already 100%, which is the upper limit SOC, the storage battery 11 is not charged and surplus power is sold.

  Then, as shown in FIG. 9, when the PV power becomes less than the load power at 17:00, the discharge rate is calculated according to the above equation (2) as the first of the daytime hours, Set the discharge current value.

  At the time of 17:00, the current time at which discharge starts (discharge start time) is 17:00, the discharge end time is 23:00, and the current (17:00) SOC is 100%, which is the upper limit SOC. Assuming that the SOC at the end of the discharge is 25%, which is the lower limit SOC, the discharge rate is calculated again, and the discharge current value is set. Specifically, it is calculated as in the following formula (8).

  The charge / discharge control device 14 calculates the storage battery output by multiplying the current storage battery voltage value of the storage battery 11 and the set discharge current value. When the storage battery output is smaller than the first difference value, the charge / discharge control device 14 starts discharging the storage battery 11 according to the set discharge current value as described above.

  And as shown in FIG. 10, in 6 hours from 17:00 to 23:00, the charging rate of the storage battery 11 was set so that the amount of decrease per unit time became constant and the lower limit SOC was 25%. The storage battery 11 will continue to be discharged at the discharge current value (3.75 A).

  Here, conventionally, unlike the first embodiment, since the storage battery is discharged according to the fluctuation of PV power and the fluctuation of load power without setting the discharge current value, the behavior of the discharge current value is controlled. could not. That is, conventionally, according to fluctuations in PV power and load power, for example, as shown in FIG. 10, the charging rate of the storage battery 11 remains constant at 100%, which is the upper limit SOC from 8:00 to 13:00. In this state, the behavior becomes 50% in 10 hours from 13:00 to 23:00, and the discharge current value cannot be controlled.

  On the other hand, in this Embodiment 1, even if it is a case where PV electric power exceeds load electric power from the morning to the evening in the daytime, the charging / discharging control apparatus 14 is that the charging rate of the storage battery 11 is daytime. The discharge current value is set so that the lower limit SOC is reached by the end time of the intermediate time zone (start time of the midnight time zone), and the storage battery 11 is discharged. Therefore, the charging rate of the storage battery 11 does not become larger than the lower limit SOC, and no extra power remains in the storage battery 11. That is, in the daytime time period, the charging power can be efficiently used until the charging rate of the storage battery 11 reaches the lower limit SOC.

  Next, the life extension effect in the charge / discharge control operation of the storage battery 11 by the charge / discharge control device 14 will be described with reference to FIG. FIG. 11 is an explanatory diagram showing a change in the capacity maintenance rate of the storage battery 11 according to Embodiment 1 of the present invention. In addition, in FIG. 11, the change of the capacity retention rate of the storage battery in the conventional storage battery system is also shown as a comparative example.

  In FIG. 11, in the conventional storage battery system, as described above, the charge / discharge current value during charging and discharging cannot be controlled. Therefore, at the time of charging in the midnight time zone, the charging end time may be shortened, and the full charge maintaining time of the storage battery may be lengthened.

  Moreover, when the PV power or the load power suddenly changes during the discharge of the storage battery 11, the discharge current value becomes unexpectedly large. As a result, as shown in FIG. 11, when the conventional storage battery system is used during a certain period, the capacity maintenance rate of the storage battery is greatly reduced.

  On the other hand, in the storage battery system 10 according to the first embodiment, the charge / discharge control operation by the charge / discharge control device 14 makes the current time for charging / discharging, the current PV power, the load power, and the storage battery state. Accordingly, the charge / discharge rate is calculated and the charge / discharge current value is set. Therefore, as a result, as shown in FIG. 11, when the storage battery system 10 is used during a certain period, the decrease in the capacity maintenance rate of the storage battery 11 becomes smaller than the conventional one, and the life of the storage battery 11 can be extended. . Furthermore, since the power charged in the storage battery 11 can be used efficiently until the charging rate of the storage battery 11 reaches the lower limit SOC in the daytime hours, the economy is improved.

  In this way, in the daytime time zone, when the current PV power is equal to or less than the current load power, the charge / discharge control device 14 is configured to store the storage battery 11 from the current time to the desired discharge end time as described above. The discharge current value is set so that the storage rate reaches the lower limit SOC, and the storage battery output of the storage battery 11 is calculated. When the calculated storage battery output is smaller than the first difference value, the charge / discharge control device 14 discharges the storage battery until the charging rate reaches the lower limit SOC value at the set discharge current value. Thereby, since the discharge current value of the storage battery 11 can be controlled, the discharge current value does not increase unexpectedly, and it is possible to prevent the storage battery from deteriorating and extend its life.

  Moreover, the charging / discharging control apparatus 14 stops operation | movement of the storage battery 11 in the daytime time zone, when the storage battery output of the storage battery 11 is more than a 1st difference value. Then, during the pause, when the current PV power is less than or equal to the current load power, as described above, the storage rate of the storage battery 11 reaches the lower limit SOC from the current time to the desired discharge end time. The discharge current value is reset and the storage battery output of the storage battery 11 is calculated. Subsequently, when the calculated storage battery output is smaller than the first difference value, the charge / discharge control device 14 discharges the storage battery until the charging rate reaches the lower limit SOC value at the reset discharge current value. As a result, even if the PV power fluctuates greatly during the daytime period, it can be discharged to the lower limit SOC at the end of charge at the desired discharge rate according to the current time. The value does not increase unexpectedly, and it is possible to prevent the storage battery from deteriorating and extend its life.

  Further, the charge / discharge control device 14 charges the storage battery 11 with surplus power in the current PV power or the storage battery 11 when the current PV power is larger than the current load power in the daytime period. Pause the operation. Thereby, since the discharge of the storage battery 11 is not performed, the discharge current value does not increase unexpectedly, and the storage battery can be prevented from deteriorating and have a long life.

  Moreover, the charge / discharge control apparatus 14 is a charge rate until the charge rate of the storage battery 11 reaches | attains an upper limit SOC value from the value of the present charge rate by the desired charge end time in a midnight time zone from the current charge rate value. The charge rate is calculated so that the increase amount per unit time is constant, and the charge current value is set. Then, the charge / discharge control device 14 charges the storage battery 11 with the set charging current value. Thereby, since the full charge maintenance time of the storage battery 11 can be controlled, the full charge maintenance time of the storage battery 11 can be reduced, and as a result, deterioration of the storage battery and long life can be achieved. Furthermore, if the desired charging start time is set as the midnight time zone start time and the desired charging end time is set as the midnight time zone end time, the full charge maintenance time of the storage battery 11 can be reduced to the minimum.

  As described above, according to the first embodiment, the charge / discharge control device in the storage battery system calculates the charge / discharge rate according to the charge / discharge time, the PV power, the load power, and the storage battery state, and calculates the charge / discharge current value. Set and perform charge / discharge control of the storage battery.

  As a result, even if a sudden change in PV power or load power occurs during charging / discharging of the storage battery, the charge / discharge current value does not increase unexpectedly, and the storage battery 11 is fully charged. Since the maintenance time can be reduced, the life of the storage battery can be extended. Moreover, since the electric power charged in the storage battery can be efficiently used in the daytime hours until the charge rate of the storage battery reaches the lower limit SOC, the economy is improved.

  DESCRIPTION OF SYMBOLS 10 Storage battery system, 11 Storage battery, 12 BMU, 13 Storage battery PCS, 14 Charge / discharge control apparatus, 20 PV system (solar power generation system), 21 PV apparatus, 22 PV PCS, 30 CT sensor, 40 load, 50 System power supply .

Claims (5)

The PV power generated in the photovoltaic power generation (PV) system, the grid power supplied from the grid power supply, and the load power consumed by the load are detected, and the charging control of the storage battery is performed in the midnight time zone, and the midnight time A storage battery charge / discharge control device that performs discharge control of the storage battery during daytime hours defined as a time zone other than the belt,
In the midnight time zone, the amount of increase in the charge rate per unit time until the charge rate of the storage battery reaches the desired upper limit SOC value from the desired charge start time to the desired charge end time is constant. By calculating a charging rate, a charging current value is set, and the storage battery is charged until the charging rate reaches the upper limit SOC value at the set charging current value,
In the daytime period, when the current PV power is less than or equal to the current load power, the charging rate until the charging rate of the storage battery reaches a desired lower limit SOC value from the current time to the desired discharge end time By calculating the first discharge rate so that the amount of decrease per unit time is constant, the first discharge current value is set, and the set first discharge current value is multiplied by the voltage of the storage battery. When the first storage battery output of the storage battery obtained in (1) is smaller than the first difference value obtained by subtracting the current PV power from the current load power, the set first discharge current value is used. A storage battery charge / discharge control device for discharging the storage battery until a charging rate reaches the lower limit SOC value. The charge / discharge control device for a storage battery according to claim 1,
In the daytime period, when the first storage battery output is greater than or equal to the first difference value, the operation of the storage battery is suspended, and the current PV power is less than or equal to the current load power during the suspension. In this case, the reduction rate per unit time until the storage rate of the storage battery reaches the desired lower limit SOC value from the current time to the desired discharge end time is set to be constant. By calculating the second discharge rate, a second discharge current value is set, and the second storage battery output of the storage battery obtained by multiplying the set second discharge current value and the storage battery voltage is the current When the current difference is smaller than the second difference value obtained by subtracting the current PV power from the load power of the battery, the storage battery is operated until the charging rate reaches the lower limit SOC value at the set second discharge current value. Discharge The charge and discharge control device for a storage battery. The storage battery charge / discharge control device according to claim 1 or 2,
In the daytime period, when the current PV power is larger than the current load power, the storage battery is charged with surplus power of the current PV power, or the operation of the storage battery is suspended. Charge / discharge control device for storage battery. In the storage battery charge / discharge control device according to any one of claims 1 to 3,
In the midnight time zone, the desired charge start time is a start time of the midnight time zone, and the desired charge end time is an end time of the midnight time zone. Detecting PV power generated in a photovoltaic power generation (PV) system, system power supplied from a system power source, and load power consumed by a load;
In the midnight hours, the charging rate is such that the amount of increase in the charging rate per unit time until the charging rate of the storage battery reaches the desired upper limit SOC value from the desired charging start time to the desired charging end time is constant. By charging the storage battery until the charging rate reaches the upper limit SOC value with the set charging current value,
In daytime hours defined as time zones other than the midnight time zone, when the current PV power is less than or equal to the current load power, the charge rate of the storage battery is desired from the current time to the desired discharge end time. The first discharge current value is set by calculating the first discharge rate so that the amount of decrease in the charging rate per unit time until reaching the lower limit SOC value is constant, and the set first discharge current is set. When the first storage battery output of the storage battery obtained by multiplying the value by the voltage of the storage battery is smaller than the first difference value obtained by subtracting the current PV power from the current load power Discharging the storage battery until the charging rate reaches the lower limit SOC value at the set first discharge current value;
A charge / discharge control method for a storage battery.

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