JP2016015803A - Load leveler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a load leveler capable of efficiently controlling a voltage state of a system power to reduce a load on a distribution line without sacrificing the function of leveling a user load.SOLUTION: A load leveler 30 has a secondary battery 32 capable of being charged and discharged, and levels a load of an electric power demand by charging and discharging the secondary battery 32, which is placed on a user side 20 of a power system 1 and which power-generating means 10A and 10B arranged to use recyclable energy are to be connected with. The load leveler 30 comprises: generation power-detecting means 33 for detecting a generation power by recyclable energy; and control means 34 for controlling the charge/discharge of the secondary battery 32. The control means 34 has the secondary battery 32 charged when the generation power exceeds a predetermined threshold in a first time zone in which a less electric power is used on the user side 20.

Description

  The present invention relates to a load leveling device that performs load leveling of power demand using a secondary battery installed in a consumer.

  In general, power consumption tends to be small at night and increased during the day. Especially in the summer, which is the peak season, the amount of power demand during the daytime hours is higher than during periods other than the peak season (see FIGS. 17 and 18). In order to eliminate such a difference in the amount of power demand between day and night, load leveling of power demand is performed. Load leveling uses, for example, a rechargeable battery that can be charged and discharged, and is charged at night when the amount of power used is low, and discharged during the day to reduce the amount of power during the day. It is to reduce (peak cut).

  In recent years, power generation facilities using renewable energy such as wind power generation and solar power generation are increasing. However, in such wind power generation and solar power generation, power output fluctuations remarkably occur depending on the strength of wind and the state of sunlight due to clouds, so it is difficult to stably supply power. For this reason, there is a concern about the influence of such power fluctuations on system power and distribution line voltage.

  Conventionally, such power fluctuations have been dealt with by controlling the output of a power generator such as thermal power generation, but there is a limit to these correspondences. The use of such secondary batteries has been proposed. However, since the secondary battery is expensive, it is not practical for a system company such as an electric power company to install it in all facilities because the burden is large. On the other hand, in power system consumers, secondary batteries are beginning to be installed in factories, office buildings and the like for load leveling of power demand. In addition, it has been proposed to use a plurality of secondary batteries to stabilize a power system (Patent Document 1).

JP 2010-233353 A

  By the way, in order to use a secondary battery efficiently, it is necessary to control the timing of charge and discharge. In the power supply system of Patent Document 1, when the amount of power generated by renewable energy (wind power generation device) exceeds the amount of power consumption, the surplus power is charged in the secondary battery. However, since reverse power is applied to the power system when charging, the system power can be in an overvoltage state. For this reason, the frequency and voltage state of the power system are detected, and various controls are performed according to the detected voltage value. For example, when the system power is in an overvoltage state, the discharge amount of the secondary battery is reduced or the power storage is performed, or the output of the wind power generator is suppressed or cut off. At this time, when performing control by the secondary battery, a priority order is determined according to the adjustment capability of the plurality of secondary batteries, and control by the power storage device (storage or Discharge).

  Thus, the electric energy of system | strain electric power can be stabilized by discharging or charging using a secondary battery. However, in the power supply system of Patent Document 1, charging and discharging of the secondary battery are controlled by charging and discharging based on the relationship between the power generation amount and the power consumption and by detecting the voltage value of the system voltage. . In particular, the control of the secondary battery by detecting the voltage value targets a plurality of secondary batteries, so that there is a problem that the system becomes large and the control becomes complicated. Further, since control is performed only after detecting whether the voltage value is below or above the appropriate range, there is a state where the voltage value is not within the appropriate range, and a load has been applied to the distribution line and the like.

  In view of the above circumstances, the technical problem to be solved by the present invention is to efficiently control the voltage state of the system power and suppress the load on the distribution line without impairing the load leveling function of the consumer. An object of the present invention is to provide a load leveling device that can perform the above.

  In order to solve the above-described problems, a load leveling apparatus according to the present invention includes a secondary battery that can be charged and discharged by being installed in a power system customer to which power generation means using renewable energy is connected. A load leveling device for leveling power demand by charging and discharging a secondary battery, wherein the generated power detection means detects the generated power using renewable energy, and charges or discharges the secondary battery. A control means for controlling, and the control means charges the secondary battery when the generated power exceeds a predetermined threshold in a first time zone in which less power is used by the consumer. It is characterized by that.

  By configuring in this way, the secondary battery is charged when the generated power using renewable energy exceeds a predetermined threshold in the first time zone where the amount of power used is low, such as at night. Therefore, power consumption can be increased. Due to the increase in power consumption, the generated power using renewable energy decreases, so the voltage state of the system power can be lowered to reduce the load on the distribution line. In addition, when the generated power using renewable energy becomes lower than a predetermined threshold, charging to the secondary battery is stopped, so the generated power using renewable energy can be increased, and the voltage state of the system power can be changed. Raise.

  At this time, the secondary battery is intermittently charged in order to perform charging when the generated power exceeds a predetermined threshold. Here, the secondary battery can use the recovery voltage by charging intermittently, and can charge more power than charging continuously. Therefore, the charge leveling function using the secondary battery can be improved by charging a large amount of power.

  Moreover, it is preferable that the power charged in the secondary battery is constant regardless of the generated power. Electric power for charging the secondary battery is converted from AC to DC and charged. Here, the converter for converting from alternating current to direct current has a power value with good conversion efficiency, and the conversion is preferably performed with a value with good conversion efficiency. Thus, the secondary battery can be efficiently charged by charging with a constant power value with good conversion efficiency.

  Further, the power charged in the secondary battery may be changed in proportion to the generated power. That is, when the difference between the generated power and the predetermined threshold is large, the charging power is increased, and when the difference between the generated power and the predetermined threshold is small, the charging power is decreased. As a result, when the difference between the generated power and the predetermined threshold is large, the power consumption increases by increasing the charging power, so that the voltage state of the system power can be greatly reduced. On the other hand, when the difference between the generated power and the predetermined threshold is small, the power consumption is not so large compared to the above by reducing the charging power, and the voltage state of the system power can be reduced gradually. it can. As described above, by changing the power charged in the secondary battery in proportion to the generated power, it is possible to efficiently suppress the fluctuation of the voltage state of the system power.

  Moreover, you may change the electric power charged to a secondary battery in steps according to generated electric power. Thereby, in addition to increasing / decreasing the charging power depending on the difference between the generated power and the predetermined threshold, the charging power in the predetermined generated power can be increased / decreased as appropriate. Here, in order to efficiently suppress fluctuations in the voltage state of the system power by charging the secondary battery, the secondary battery is supplied over the entire period from the beginning to the end time of the first time zone. It is preferable to perform charging. Therefore, the amount of charge is controlled so that charging to the secondary battery is not completed in the middle of the first time period by increasing or decreasing the amount of charging power in the predetermined generated power according to the amount of charging of the secondary battery. Can do. In addition, since charging electric power is increased / decreased according to generated electric power, the fluctuation | variation of the voltage state of system electric power can be suppressed efficiently like the above.

  Further, the control means determines whether or not the state of charge of the secondary battery has reached a predetermined reference value every predetermined time in the first time zone, and determines that the predetermined reference value has not been reached. May lower the threshold by a predetermined amount, and maintain the threshold when it is determined that the predetermined reference value has been reached. For example, if the generated power continues to be smaller than a predetermined threshold, the secondary battery is not sufficiently charged. Therefore, the charging of the secondary battery may not be completed at the end of the first time zone for charging. Then, the voltage state of the system power cannot be sufficiently suppressed by the charged power of the secondary battery. Therefore, it is confirmed whether or not the state of charge of the secondary battery has reached a predetermined reference value every predetermined time, and if the charge amount has not reached the predetermined reference value within the predetermined time, the threshold value for charging is set. Lowering makes it easier to charge. Thereby, charging can be performed frequently in the first time zone, and charging can be reliably completed at the end of the first time zone. As a result, it is possible to efficiently suppress the voltage state of the system power using the charged secondary battery. In addition, when the charging state of the secondary battery has reached a predetermined reference value, it is possible to continue charging under the same conditions by maintaining the predetermined threshold value.

  Further, the control means determines whether or not the state of charge of the secondary battery has reached a predetermined reference value every predetermined time in the first time zone, and determines that the predetermined reference value has been reached. May increase the threshold by a predetermined amount, and decrease the threshold by a predetermined amount when it is determined that the predetermined reference value has not been reached. For example, contrary to the above, when the state where the generated power is larger than a predetermined threshold continues, the secondary battery is continuously charged. For this reason, the charging of the secondary battery may be completed at the beginning or midway of the first time zone in which charging is performed. Then, at the end of the first time zone, it becomes impossible to suppress fluctuations in the voltage state of the system power due to charging of the secondary battery. Therefore, it is confirmed whether or not the state of charge of the secondary battery has reached a predetermined reference value every predetermined time, and if the amount of charge has reached the predetermined reference value within the predetermined time, the threshold value for charging is set. By making it rise, it makes charging difficult. As a result, charging to the secondary battery is not completed early, and charging can be performed over time. In addition, when the charge amount does not reach the predetermined reference value within the predetermined time, similarly to the above, charging is performed reliably by frequently charging by lowering the threshold value. In this way, the voltage state of the system power is efficiently suppressed by charging the secondary battery.

  Here, the predetermined threshold value is preferably set based on the tendency of the generated power grasped in advance. Since renewable energy uses natural energy, the power generated using renewable energy is not constant and varies. Therefore, for example, by grasping the trend of the generated power for each season and setting a predetermined threshold based on the trend, an appropriate threshold of the generated power obtained at that time can be set. Thereby, the charging of the secondary battery and the control of the voltage state of the system power can be performed more efficiently.

  Further, the first time zone is set longer than the charging time required to charge the target charge amount to the secondary battery, and the control means sets the charge amount and the target charged to the secondary battery at a predetermined time point. The remaining charge until the charge is completed is calculated from the charge amount, and the remaining charge time required to charge the remaining charge is determined based on the relationship between the charge amount of the secondary battery and the charge time obtained in advance. Compare the remaining time from the predetermined time to the end of the first time period with the remaining charge time.If the remaining time matches the remaining charge time, the secondary battery is continuously charged during the remaining time. You may go. Here, since the generated power fluctuates irregularly and uncertainly, if it often falls below a predetermined threshold, charging may not be completed when the first time period ends. Therefore, the relationship between the amount of charge to the secondary battery and the charging time is obtained in advance, and the remaining time from the predetermined time until the end of the first time zone is compared with the remaining charging time until the charging is completed. When the remaining time matches the remaining charging time, the remaining time is continuously charged. Thereby, at the end of the first time zone, the charging of the secondary battery can be reliably completed.

  On the other hand, in order to solve the above-mentioned problem, a load leveling device according to the present invention includes a secondary battery that can be charged and discharged by being installed at a customer of an electric power system to which power generation means using renewable energy is connected. A load leveling device that performs load leveling of power demand by charging and discharging a secondary battery, the generated power detection means for detecting the generated power using renewable energy, and charging or charging the secondary battery Control means for controlling the discharge, and the control means discharges the secondary battery when the generated power is below a predetermined threshold in a second time zone in which a large amount of power is used by the consumer. It is characterized by performing.

  By configuring in this way, the secondary battery is discharged when the generated power using renewable energy falls below a predetermined threshold in the second time period when there is a large amount of power used, such as during the daytime. Therefore, the power supply can be increased. By increasing the supply of electric power, the voltage state of the system power can be increased, and a decrease in load on the distribution line can be suppressed. In addition, when the generated power using renewable energy becomes higher than a predetermined threshold, the discharge from the secondary battery is stopped, so that the generated power using renewable energy can be reduced, and the voltage state of the system power can be reduced. Lower.

  At this time, since the discharge is performed when the generated power falls below a predetermined threshold, the secondary battery is intermittently discharged. Here, the secondary battery can use the recovery voltage by discharging intermittently, and can discharge more power than continuous discharge. Therefore, by discharging a large amount of power, the load leveling function using the secondary battery can be improved.

  Moreover, it is preferable to make constant the electric power which a secondary battery discharges irrespective of generated electric power. The electric power discharged from the secondary battery is converted from direct current to alternating current and discharged. Here, the converter for converting from direct current to alternating current has a power value with good conversion efficiency, and the conversion is preferably performed with a value with good conversion efficiency. Thus, the secondary battery can be efficiently discharged by discharging at a constant power value with good conversion efficiency.

  Furthermore, the power discharged from the secondary battery may be changed in proportion to the generated power. That is, when the difference between the generated power and the predetermined threshold is large, the discharge power is increased, and when the difference between the generated power and the predetermined threshold is small, the discharge power is decreased. As a result, when the difference between the generated power and the predetermined threshold is large, the supply amount of power increases by increasing the discharge power, so that the voltage state of the system power can be greatly increased. On the other hand, when the difference between the generated power and the predetermined threshold is small, the amount of power supplied is not so large compared to the above by reducing the discharge power, and the voltage state of the system power can be increased gradually. it can. As described above, by changing the power discharged from the secondary battery in proportion to the generated power, it is possible to efficiently suppress the fluctuation of the voltage state of the system power.

  Moreover, you may change the electric power which a secondary battery discharges in steps according to generated electric power. Thereby, in addition to increasing / decreasing the discharge power depending on the difference between the generated power and the predetermined threshold, the discharge power in the predetermined generated power can be appropriately increased / decreased. Here, in order to efficiently suppress fluctuations in the voltage state of the system power by discharging from the secondary battery, from the secondary battery over the entire period from the beginning to the end time of the second time zone. It is preferable to perform the discharge. Therefore, the discharge amount is controlled so that the discharge from the secondary battery is not completed in the middle of the second time period by increasing or decreasing the discharge power in the predetermined generated power according to the discharge amount of the secondary battery. Can do. In addition, since discharge electric power is increased / decreased according to generated electric power, the fluctuation | variation of the voltage state of system electric power can be suppressed efficiently like the above.

  Further, the control means determines whether or not the discharge state of the secondary battery has reached a predetermined reference value every predetermined time in the second time zone, and determines that the predetermined reference value has not been reached. May increase the threshold by a predetermined amount, and maintain the threshold when it is determined that the predetermined reference value has been reached. For example, if the generated power continues to be larger than a predetermined threshold, the secondary battery is not sufficiently discharged. Therefore, the discharge from the secondary battery may not be completed at the end of the second time period during which discharge is performed. As a result, the voltage state of the system power cannot be sufficiently suppressed. Therefore, it is confirmed whether or not the discharge state of the secondary battery has reached a predetermined reference value every predetermined time. If the discharge amount has not reached the predetermined reference value within the predetermined time, the threshold value for discharging is set. Increasing it makes it easier for discharge to occur. Thus, frequent discharge can be performed in the second time zone, and the discharge can be reliably completed at the end of the second time zone. As a result, the voltage state of the system power due to the discharge can be efficiently suppressed. In addition, when the discharge state of the secondary battery has reached a predetermined reference value, the discharge can be continuously performed under the same conditions by maintaining the predetermined threshold value.

  Further, the control means determines whether or not the discharge state of the secondary battery has reached a predetermined reference value every predetermined time in the second time zone, and determines that the predetermined reference value has been reached. May decrease the threshold by a predetermined amount, and increase the threshold by a predetermined amount when it is determined that the predetermined reference value has not been reached. For example, contrary to the above, when the state where the generated power is smaller than a predetermined threshold continues, the secondary battery is continuously discharged. For this reason, the discharge from the secondary battery may be completed in the initial stage or in the middle of the second time period during which the discharge is performed. Then, at the end of the second time zone, it becomes impossible to suppress fluctuations in the voltage state of the system power due to the discharge from the secondary battery. Therefore, it is confirmed whether or not the discharge state of the secondary battery has reached a predetermined reference value every predetermined time. If the discharge amount has reached the predetermined reference value within the predetermined time, the threshold value for discharging is set. Lowering makes it difficult to discharge. As a result, the discharge from the secondary battery is not completed early, and the discharge can be performed over time. When the discharge amount does not reach the predetermined reference value within the predetermined time, the discharge is surely performed by increasing the threshold value and performing frequent discharge in the same manner as described above. In this way, the voltage state of the system power due to the discharge from the secondary battery is efficiently suppressed.

  Here, the predetermined threshold value is preferably set based on the tendency of the generated power grasped in advance. Since renewable energy uses natural energy, the power generated using renewable energy is not constant and varies. Therefore, for example, by grasping the trend of the generated power for each season and setting a predetermined threshold based on the trend, an appropriate threshold of the generated power obtained at that time can be set. Thereby, it is possible to more efficiently control the discharge from the secondary battery and the voltage state of the system power.

  Further, the second time zone is set longer than the discharge time required to discharge the target discharge amount from the secondary battery, and the control means sets the discharge amount discharged from the secondary battery at the predetermined time point and the target amount. The remaining amount of discharge until the discharge is completed is determined from the discharge amount, and the remaining discharge time required to discharge the remaining discharge amount is determined based on the relationship between the discharge amount of the secondary battery and the discharge time obtained in advance. Compare the remaining time from the predetermined time to the end of the second time period with the remaining discharge time, and if the remaining time matches the remaining discharge time, the secondary battery is continuously discharged from the remaining time. You may go. Here, since the generated power fluctuates irregularly and uncertainly, if it often exceeds a predetermined threshold, there is a possibility that the discharge will not be completed when the second time period ends. Therefore, the relationship between the amount of discharge from the secondary battery and the discharge time is obtained in advance, and the remaining time from the predetermined time until the end of the second time zone is compared with the remaining discharge time until the discharge is completed. When the remaining time matches the remaining discharge time, the remaining time is continuously discharged. Thereby, at the end of the second time zone, the discharge from the secondary battery can be reliably completed.

  As described above, according to the present invention, load leveling that can efficiently control the voltage state of the system power and suppress the load on the distribution line without impairing the load leveling function of the consumer. An apparatus can be provided.

It is the schematic which shows the state which connected the load leveling apparatus concerning one Embodiment of this invention to the electric power grid | system. Explanatory drawing which shows the timing of charge of a secondary battery in the load leveling apparatus concerning FIG. Explanatory drawing which shows the relationship between time and the voltage at the time of charge to said secondary battery. Explanatory drawing which shows electric power with favorable conversion efficiency in the converter used for the load leveling apparatus concerning FIG. In said secondary battery, explanatory drawing which shows the relationship between charge remaining charge and charge remaining time. Explanatory drawing which put together the relationship between the time in the load leveling apparatus concerning FIG. 1, generated electric power, charging power, and charging amount. (A)-(c) Explanatory drawing which shows the relationship between generated electric power and charging electric power in charge to said secondary battery. (A)-(c) Explanatory drawing which shows the relationship between time and the threshold value of generated electric power in charge to said secondary battery. (A)-(c) Explanatory drawing which shows the other example of the relationship between time and the threshold value of generated electric power in charge to said secondary battery. Explanatory drawing which shows the relationship between the moon and the threshold value of generated electric power in the load leveling apparatus concerning FIG. Explanatory drawing which shows the timing of the discharge of a secondary battery in the load leveling apparatus concerning FIG. Explanatory drawing which shows the relationship between time and a voltage in the case of discharge from said secondary battery. In said secondary battery, explanatory drawing which shows the relationship between discharge residual amount and discharge remaining time. Explanatory drawing which put together the relationship between the time in the load leveling apparatus concerning FIG. 1, generated electric power, discharge electric power, and discharge amount. (A)-(c) Explanatory drawing which shows the relationship between generated electric power and discharge electric power in discharge from said secondary battery. (A)-(c) Explanatory drawing which shows the relationship between time and the threshold value of generated electric power in discharge from said secondary battery. (A)-(c) Explanatory drawing which shows the other example of the relationship between time and the threshold value of generated electric power in discharge from said secondary battery. Explanatory drawing which shows the example of the conventional load leveling in the peak period. Explanatory drawing which shows the example of the load leveling in the past except the peak period.

  Hereinafter, an embodiment of a load leveling apparatus according to the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic diagram illustrating a state in which a load leveling device according to an embodiment of the present invention is connected to a power system. The power system 1 is an entire facility that performs power generation (power generation) to consumption, and a power generation facility 10 that generates power and a consumer 20 that consumes power are connected via a transmission line 11.

  The power generation facility 10 is a facility owned by a system operator, and generates power by various methods such as thermal power generation, hydropower generation, and nuclear power generation. A power transmission line 11 that transmits the generated power is connected to the power generation facility 10. The power transmission line 11 transmits the power generated by the power generation facility 10 via the substation 12 and the transformer 13. Here, the substation 12 is a facility that converts the voltage and frequency of the power generated by the power generation facility 10, and the transformer 13 is a device that further converts the voltage.

  The power transmission line 11 is connected to other power generation facilities such as a solar power generation 10A and a wind power generation 10B. The solar power generation 10A and the wind power generation 10B are facilities that generate power using renewable energy such as sunlight and wind power. Unlike the power generation facility 10 owned by the grid operator, these facilities are small-scale facilities, and are installed in a factory or an office building.

  The customer 20 is a facility that is connected to the power transmission line 11 to receive and consume power. Hereinafter, in the electric power system 1, electric power consumers who are supplied with electric power, such as large facilities such as factories and buildings, and private homes, are collectively referred to as consumers 20.

  The load leveling device 30 is installed in the facility of the customer 20. Further, the load leveling device 30 includes a secondary battery 32 that can be charged and discharged via a converter 31, a generated power detection means 33 that detects generated power using renewable energy, a secondary battery 32, and And control means 34 connected to the generated power detection means 33.

  The converter 31 is a device that mutually converts AC power and DC power, and specifically has a function of a converter that converts AC power to DC power and a function of an inverter that converts DC power to AC power. . In the present embodiment, system power, which is AC power, is converted to DC power to charge the secondary battery 32, and DC power stored in the secondary battery 32 is converted to AC voltage to generate power. Discharge to system 1.

  The secondary battery 32 stores power by charging and supplies power by discharging. For example, a livestock battery with less self-discharge, such as a well-known lithium ion battery or sodium sulfur battery, is preferable. Here, when the secondary battery 32 is charged, a charge amount slightly lower than the full charge is set as the target charge amount for the chargeable capacity, and the target charge is set at the end of the first time zone. Charge to the amount. Further, at the time of discharging, the charged electric power is set to be completely discharged, and discharging is performed so as to be completely discharged at the end of the second time zone.

  The generated power detection means 33 is means for detecting the generated power by a known method. In the present embodiment, the power generation using renewable energy is detected by being connected to the solar power generation 10A and the wind power generation 10B. Hereinafter, generated power using renewable energy is referred to as generated power.

  The control unit 34 is connected to the secondary battery 32 and the generated power detection unit 33. The control unit 34 switches between charging and discharging of the secondary battery 32 based on time information acquired by a clock (not shown). Further, based on the value of the generated power detected by the generated power detection means 33, the timing of charging or discharging the secondary battery 32 is controlled. As described above, the control unit 34 performs various controls on the load leveling device 30. Details of control of charging or discharging the secondary battery 32 by the control unit 34 will be described later.

  Next, the operation of the load leveling device 30 will be described. The load leveling device 30 charges the secondary battery 32 at night as a first time zone where the power consumption is low, and the secondary battery 32 during the daytime as a second time zone when the power usage is high. By performing discharge from the power source, load leveling of power demand is performed. In the present embodiment, the first time zone is from 10 pm (22:00) to 8 am, and the second time zone is from 8 am to 10 pm. Note that, as described above, switching between discharging and charging of the secondary battery 32 is performed by the control means 34.

  Hereinafter, the details of the control of charging the secondary battery 32 in the first time zone performed by the control unit 34 will be described. FIG. 2 shows the relationship between the time of the first time zone and the generated power, and the charging timing of the secondary battery 32. Here, in the first time zone, wind power generation 10B is used as renewable energy. The generated power fluctuates irregularly, and the generated power fluctuation shown in FIG. 2 shows an example.

  The secondary battery 32 is charged when the generated power exceeds a predetermined threshold, as shown in FIG. In the present embodiment, the predetermined threshold is 50 kW. The generated power detection means 33 detects the generated power and transmits the detected value to the control means 34. The control unit 34 charges the secondary battery 32 when the generated power exceeds a predetermined threshold (50 kW) set in advance, and stops charging the secondary battery 32 when the generated power falls below the predetermined threshold. Thus, since the secondary battery 32 is charged when the generated power exceeds a predetermined threshold, the power consumption in the power system 1 increases. Therefore, the voltage state of the system power can be changed in a decreasing direction.

  As shown in FIG. 2, in the first time zone (22:00 to 8:00), the generated power exceeds a predetermined threshold in the time zone from 22:00 to time a and from time b to time c. The secondary battery 32 is charged. In addition, after the time d, charging is performed even in a state where the generated power is below the threshold, but details will be described later.

  Thus, since the secondary battery 32 is charged when the generated power exceeds a predetermined threshold, the secondary battery 32 is intermittently charged. FIG. 3 shows the relationship between time and voltage when the secondary battery 32 is charged. As illustrated, the charging of the secondary battery 32 is intermittently performed until the voltage reaches a predetermined value (predetermined voltage). Here, the voltage rises while the secondary battery 32 is charged. On the other hand, while the battery is not charged, the voltage of the secondary battery 32 decreases. This is called the recovery voltage. The voltage measured during charging is a value measured including the internal resistance, and the voltage increases by the amount of the internal resistance. However, since the measured value during the charge stop does not include the internal resistance, a substantial voltage of the secondary battery 32 is indicated. Therefore, if the secondary battery 32 is intermittently charged, the recovery voltage can be used as compared with the case where the secondary battery 32 is continuously charged. Therefore, the amount of power that can be charged in the secondary battery 32 can be increased.

  Further, since the system power is alternating current, it is converted into direct current by the converter 31 (see FIG. 1) and charged to the secondary battery 32. Here, as shown in FIG. 4, the converter 31 has a range of electric power with good conversion efficiency. For example, if the rating (upper limit) of the converter 31 is 100 kW, the conversion efficiency is good at 60 kW to 100 kW. In the present embodiment, AC system power is converted to 80 kW using a converter 31 with a rating of 100 kW. As a result, the secondary battery 32 is charged with 80 kW of DC power.

  Here, charging after time d in FIG. 2 will be described. As described above, when the secondary battery 32 is charged when the generated power exceeds the predetermined threshold, the fluctuation of the generated power is irregular and uncertain, so the time during which the generated power exceeds the predetermined threshold If the amount is small, the charging time cannot be sufficiently taken, and there is a possibility that the charging will not be completed before the first time period ends. Therefore, the control unit 34 performs control so that the secondary battery 32 is continuously charged when the end time of the first time zone approaches. Note that the first time zone is set longer than the charging time required to charge the secondary battery 32 with the target charge amount.

  The control of the control means 34 when the end time of the first time zone is near will be described in detail below. First, the remaining amount until the charging is completed (hereinafter referred to as the remaining charge amount) is obtained from the amount of charge charged in the secondary battery 32 at a predetermined time and the target amount of charge. Further, the relationship between the amount of charge to the secondary battery 32 and the charging time is obtained in advance. From this relationship, the time required to charge the remaining charge (hereinafter referred to as remaining charge time) is obtained. Furthermore, when the remaining time from the predetermined time point until the end of the first time period is compared with the remaining charge time and the remaining time matches the remaining charge time, the remaining time The battery 32 is continuously charged.

  FIG. 5 shows the relationship between the remaining charge of the secondary battery 32 and the remaining charge time. This relationship is the same as the relationship between the charge amount and the charge time, and indicates the charge time until the target charge amount is reached from the predetermined charge amount. Here, if the vertical axis corresponds to the time of the first time zone in which the secondary battery 32 is charged, the point indicating the predetermined time and the remaining charge at that time is in the region above the straight line in the figure. Once located, charging can be completed by the end of the first time period. In this case, since it is not necessary to perform charging continuously, charging is performed by the above control. However, if the point indicating the predetermined time and the remaining charge at that time is located in the area below the straight line in the figure, charging will be completed by the end of the first time zone even if charging is performed thereafter Can not do. Therefore, when the point indicating the predetermined time and the remaining charge amount at that time is located on the straight line in the figure, it is necessary to start charging and continuously charge until charging is completed.

  Here, a to d shown in FIG. 5 indicate time points corresponding to the respective times shown in FIG. At the time point a, the secondary battery 32 is already charged by a predetermined amount, and is not charged between a and b. At this time, charging is not performed between a and b, but since time has elapsed, in FIG. 5, only the remaining charge time decreases between a and b. In addition, the secondary battery 32 is charged between b and c. During charging, both the remaining charge and the remaining charge time decrease in parallel with the straight line shown in the figure.

  Further, at time c, since the generated power falls below a predetermined threshold as shown in FIG. 2, charging of the secondary battery 32 is stopped. Thereafter, the remaining charge time decreases with the remaining charge remaining at time c (see FIG. 2). As time elapses, it overlaps with the straight line shown in FIG. 5 (indicated by d in FIG. 5). As described above, due to the relationship between the remaining charge time and the remaining charge shown in FIG. 5, it is necessary to continuously charge after the time point d. Therefore, the control means 34 starts charging the secondary battery 32 at the time point d. After this, charging is continuously performed until charging is completed without controlling charging with generated power. By controlling in this way, the charging of the secondary battery 32 can be reliably completed at the end of the first time period. Note that the relationship between the amount of charge and the charging time in the secondary battery 32 (see FIG. 5) changes depending on the change over time of the secondary battery 32, and therefore is updated to the latest information by appropriately measuring.

  For charging the secondary battery 32 performed as described above, various controls by the control means 34, changes in the charge amount, and the like are collectively shown in FIG. Specifically, FIG. 6 shows the relationship between the time of the first time zone, the generated power, the charged power, and the charge amount. As described above, charging of the secondary battery 32 is performed when the generated power exceeds a predetermined threshold (50 kW) (until time a, times b to c). The charging power at this time is 80 kW. At this time, the charge amount gradually increases until the target charge amount is reached. Furthermore, when the remaining time in the first time period decreases (time d), charging is started and charging is continued even if the generated power is below a predetermined threshold. In this way, it is possible to efficiently charge the secondary battery 32 in the first time zone.

  In the above embodiment, the charging power is set to 80 kW and a constant value as shown in FIG. 7A. However, the present invention is not limited to this. For example, the power for charging the secondary battery 32 may be changed in proportion to the generated power. As shown in FIG. 7B, for example, for the generated power from 50 kW to 100 kW, the charging power changes within a range in which the converter 31 has good conversion efficiency (60 kW to 100 kW: see FIG. 4). It is preferable to make it. As a result, when the difference between the generated power and the predetermined threshold is large, the charging power increases, so that the amount of power consumed in the power system increases and the voltage state of the system power is promoted to decrease. On the other hand, when the difference between the generated power and the predetermined threshold is small, the charging power is small. In this case, since the power consumption is not so large as compared with the above, the voltage state of the system power can be lowered gently without being suddenly lowered. In this way, by changing the power charged in the secondary battery 32 in proportion to the generated power, it is possible to efficiently suppress fluctuations in the voltage state of the system power.

  Note that the ratio between the charging power of the secondary battery 32 and the generated power may be changed according to the state of charge (SOC: State Of Charge) of the secondary battery 32. As shown by a broken line in FIG. 7B, when the amount of charge of the secondary battery 32 is large (indicated by high SOC in FIG. 7B), the ratio between the charged power and the generated power is reduced. The secondary battery 32 is not charged so much. On the other hand, when the amount of charge of the secondary battery 32 is small (indicated by low SOC in FIG. 7 (b)), the secondary battery 32 has more charge by increasing the ratio of charge power and generated power. Charge the battery.

  Moreover, you may change the electric power which charges the secondary battery 32 in steps according to generated electric power. The relationship between the generated power and the charged power in this case is shown in FIG. Thereby, the charging power in predetermined generated electric power can be increased / decreased suitably. In the figure, in the generated power in which the charging power extends in the vertical direction, the charging power can be increased or decreased as appropriate even if the generated power is the same. Thus, the charging amount is increased or decreased in consideration of the remaining amount of charge of the secondary battery 32 and the remaining time of the first time zone, thereby reliably completing the charging within the first time zone. Can do. For example, when the amount of charge is small with respect to the remaining time, charging can be performed quickly by increasing the charging power and charging with a predetermined generated power. Further, when the amount of charge is large with respect to the remaining time, the charging time can be extended by performing charging by reducing the charging power at a predetermined generated power. In this example as well, since the amount of charge to the secondary battery 32 is increased or decreased according to the generated power, fluctuations in the voltage state of the system power can be efficiently suppressed as described above.

  Furthermore, in the above embodiment, the threshold value of the generated power when charging the secondary battery 32 is 50 kW, but is not limited thereto. The threshold value of the generated power may be changed according to the state of charge of the secondary battery 32 every predetermined time. In the present embodiment, the state of charge of the secondary battery 32 is detected every hour to determine whether or not a predetermined reference value (10%) has been reached. As shown in FIG. 8A, from 22:00 to 23:00, the threshold value of the generated power is set to 50 kW, and charging is performed when the threshold value is exceeded. When one hour has elapsed, it is determined whether or not the charge amount of the secondary battery 32 has reached 10%, and if it is determined that the amount has not reached, the control unit 34 determines for the next hour (23:00 to 24:00). Lowers the threshold by 1 kW and sets it to 49 kW (see FIG. 8B). Similarly, after 1 hour has passed, it is determined whether or not the charge amount of the secondary battery 32 has reached 20%. If it has reached, the threshold value is set to 48 kW, and the same is repeated thereafter. When the threshold value of the generated power is continuously lowered every hour, the threshold value at the time of 7 o'clock is set to 41 kW at the minimum (see FIG. 8C). On the other hand, when the amount of charge of the secondary battery 32 has not reached the predetermined reference value when one hour has elapsed, the set threshold value of the generated power is maintained as it is.

  In this way, when the amount of charge of the secondary battery 32 has reached a predetermined reference value after a predetermined time has elapsed, the threshold value is decreased by a predetermined amount, so that the generated power exceeds the predetermined threshold value. Even when the operation continues, charging can be prevented from being completed in the middle of the first time period. If the charging of the secondary battery 32 is completed in the middle of the first time period, the voltage state of the system power cannot be controlled by charging the secondary battery 32 thereafter. Therefore, it is possible to efficiently suppress the voltage state of the system power by charging the secondary battery 32 by preventing the charging from being completed in the middle of the first time period.

  Further, when the amount of charge of the secondary battery 32 has reached a predetermined value when a predetermined time has elapsed, the threshold value of the generated power may be increased. In this case, as shown in FIG. 9A, the threshold value of the generated power is set to 45 kW from 22:00 to 23:00. In a state where 1 hour has passed, it is determined whether or not the charge amount of the secondary battery 32 has reached 10%. If it is determined that it has reached, the threshold is increased by 1 kW and set to 46 kW. If it is determined, the threshold value is lowered by 1 kW and set to 44 kW as described above (see FIG. 9B). The same determination and threshold setting are repeated every hour. Thus, for example, when the amount of charge to the secondary battery 32 is large, the threshold at the time of 7 o'clock is 54 kW, and when the amount of charge is small, the threshold at the time of 7 o'clock is 36 kW (FIG. 9). (See (c)). By doing in this way, the charge to the secondary battery 32 can be completed reliably. If the charge amount of the secondary battery 32 is exactly 10% after 1 hour has elapsed since 22:00, the threshold value is maintained, and similarly, when the charge amount per hour is equal to the predetermined value. The threshold setting at that time may be maintained as it is.

  Thus, the amount of charge to the secondary battery 32 in the first time zone can be changed by changing the charging power to the secondary battery 32 and the threshold value of the generated power at the time of charging. In addition, charging can be performed over the entire first time period, and charging can be completed at the end of the first time period. In addition, in consideration of the relationship between the charging time and the charging amount shown in FIG. 5, when the remaining time until the first time period ends and the remaining charging time coincide with each other, the charging is continuously performed. By using together, charging can be completed more reliably at the end of the first time period.

  In addition, the threshold value of the generated power for charging the secondary battery 32 is not limited to the value set above, and can be set as appropriate. In addition, the threshold value is set to a small value (for example, 41 kW) at the beginning of the first time period, and is controlled so that the threshold value is increased when the charge amount has not reached the predetermined reference value after a predetermined time has elapsed. Also good. Further, when the threshold value is raised or lowered, the amount of change may be changed instead of being changed for every fixed value. Thus, the timing and amount of charge to the secondary battery 32 within the first time zone can be controlled by appropriately changing the threshold values of the charge power and generated power. Thereby, it is possible to efficiently suppress the change in the voltage state of the system power at night.

  Further, the threshold value for charging the secondary battery 32 may be set based on a tendency (trend) of generated power grasped in advance. Since renewable energy uses natural energy (in this embodiment, wind power), the generated power using the renewable energy is not constant and varies. However, in the long term, natural energy has a tendency. Therefore, for example, it is possible to grasp the average wind speed for each season, obtain the tendency of the generated power for each season based on the average wind speed, and set a predetermined threshold based on the tendency.

  FIG. 10 shows the relationship between the month in one year and the threshold value of the generated power. Here, the threshold value of the generated power is set based on the average wind speed every season, that is, every three months. As a result, the threshold value used as a reference for whether or not to charge the secondary battery is set based on the tendency of the generated power at that time, so the threshold value can be set appropriately, and the secondary battery can be charged. Thus, the voltage state of the system power can be controlled more efficiently.

  Next, details of the control of the discharge from the secondary battery 32 in the second time zone performed by the control unit 34 will be described. FIG. 11 shows the relationship between the time of the second time zone and the generated power, and the timing of discharge from the secondary battery 32. Here, in the second time zone, solar power generation 10A and wind power generation 10B are used as renewable energy. Note that the generated power fluctuates irregularly, and the fluctuation of the generated power shown in FIG. 11 is an example.

  As shown in FIG. 11, the secondary battery 32 is discharged when the generated power falls below a predetermined threshold. In the present embodiment, the predetermined threshold is 40 kW. The generated power detection means 33 detects the generated power and transmits the detected value to the control means 34. The control means 34 discharges from the secondary battery 32 when the generated power falls below a predetermined threshold (40 kW) set in advance, and stops discharging from the secondary battery when it exceeds the predetermined threshold. . Thus, since the secondary battery 32 is discharged when the generated power falls below a predetermined threshold, the power supply amount in the power system 1 increases. Therefore, it can be varied in the direction of increasing the voltage state of the system power.

  As shown in FIG. 11, in the second time zone (8:00 to 22:00), the generated power is below a predetermined threshold in the time zone from 8:00 to time e and from time f to time g. The secondary battery 32 is discharged. In addition, after time h, discharge is performed even in a state where the generated power exceeds the threshold value, but details will be described later.

  Thus, since the secondary battery 32 is discharged when the generated power is lower than the predetermined threshold, the secondary battery 32 is intermittently discharged. FIG. 12 shows the relationship between time and voltage when the secondary battery 32 is discharged. As illustrated, the discharge from the secondary battery 32 is intermittently performed until the voltage reaches a predetermined value (predetermined voltage). Here, the voltage decreases while the secondary battery 32 is discharged. On the other hand, while the battery is not discharged, the voltage of the secondary battery 32 rises. This is called the recovery voltage. The voltage measured during discharge is a value measured including the internal resistance, and the voltage decreases by the amount of the internal resistance. However, since the measured value when the discharge is stopped does not include the internal resistance, a substantial voltage of the secondary battery 32 is indicated. Therefore, when the secondary battery 32 is intermittently discharged, the recovery voltage can be used as compared with the case where the secondary battery 32 is continuously discharged, so that the time until the predetermined voltage is reached becomes longer. Therefore, the amount of power that can be discharged from the secondary battery 32 can be increased.

  Moreover, since the secondary battery 32 is direct current, it is converted into alternating current by the converter 31 (refer FIG. 1), and is discharged to an electric power grid | system. The characteristic of the converter 31 has a range of efficient power as shown in FIG. 4 as described above. In the present embodiment, the DC power of the secondary battery 32 is converted to 60 kW using the converter 31 having a rating of 100 kW. As a result, 60 kW of AC power is discharged to the power system 1.

  Here, the discharge after time h in FIG. 11 will be described. As described above, when the secondary battery 32 is discharged when the generated power falls below the predetermined threshold, the fluctuation of the generated power is irregular and uncertain, so the time when the generated power falls below the predetermined threshold. When there is little, discharge time cannot fully be taken and there exists a possibility that discharge may not be completed by the end of a 2nd time slot | zone. Therefore, the control unit 34 performs control so that the secondary battery 32 is continuously discharged when the end time of the second time zone approaches. The second time period is set longer than the discharge time necessary for discharging the target discharge amount from the secondary battery 32.

  The control of the control means 34 when the end time of the second time zone is near will be described in detail below. First, the remaining amount until the discharge is completed (hereinafter referred to as the remaining discharge amount) is obtained from the discharge amount discharged from the secondary battery 32 at a predetermined time point and the target discharge amount (complete discharge). Further, the relationship between the discharge amount from the secondary battery 32 and the discharge time is obtained in advance. From this relationship, a time required to discharge the remaining discharge (hereinafter referred to as remaining discharge time) is obtained. Further, the remaining time from the predetermined time point until the end of the second time period is compared with the remaining discharge time. If the remaining time matches the remaining discharge time, the remaining time is The secondary battery 32 is continuously discharged.

  FIG. 13 shows the relationship between the remaining discharge amount of the secondary battery 32 and the remaining discharge time. This relationship is the same as the relationship between the discharge amount and the discharge time, and the discharge time from the predetermined discharge amount until reaching the target discharge amount is shown. Here, when the vertical axis corresponds to the time of the second time zone in which the discharge from the secondary battery 32 is performed, the point indicating the predetermined time and the remaining amount of discharge at that time is a region above the straight line in the figure. If it is located, the discharge can be completed by the end of the second time period. In this case, since the discharge does not have to be performed continuously, the discharge by the above control is performed. However, if the point indicating the predetermined time and the remaining amount of discharge at that time is located in the area below the straight line in the figure, the discharge will be completed by the end of the second time zone even if discharge is performed thereafter Can not do. For this reason, when the point indicating the predetermined time and the remaining amount of discharge at that time is located on the straight line shown in the figure, it is necessary to start discharging and continuously discharge until discharging is completed.

  Here, e to h illustrated in FIG. 13 indicate time points corresponding to the respective times illustrated in FIG. 11. At the time point e, the secondary battery 32 is discharged by a predetermined amount, and is not discharged between e and f. At this time, although no discharge is performed between e and f, since time has elapsed, only the remaining discharge time is decreased between e and f in FIG. Further, the secondary battery 32 is discharged between f and g. During discharge, both the remaining amount of discharge and the remaining discharge time decrease in parallel with the straight line shown in the figure.

  Further, at time point g, since the generated power exceeds a predetermined threshold as shown in FIG. 11, the discharge from the secondary battery 32 is stopped. Thereafter, the remaining discharge time decreases with the amount of discharge at time g (see FIG. 11) remaining unchanged. As time elapses, it overlaps with the straight line shown in FIG. 11 (indicated by h in FIG. 13). As described above, due to the relationship between the discharge time and the remaining amount of discharge shown in FIG. 11, it is necessary to continuously discharge after the time point h. Therefore, the control means 34 starts discharging from the secondary battery 32 at the time point h. After that, the discharge is continuously performed until the discharge is completed without controlling the discharge by the generated power. By controlling in this way, the discharge from the secondary battery 32 can be reliably completed at the end of the second time zone. Note that the relationship between the discharge amount and the discharge time in the secondary battery 32 (see FIG. 13) changes depending on the change over time of the secondary battery 32, and is updated to the latest information by appropriately measuring.

  For discharge from the secondary battery 32 performed as described above, various controls by the control means 34, changes in discharge amount, and the like are collectively shown in FIG. Specifically, FIG. 14 shows the relationship between the time of the second time zone, the generated power, the discharged power, and the discharge amount. As described above, the discharge from the secondary battery 32 is performed when the generated power falls below a predetermined threshold (40 kW) (until time e, times f to g). The discharge power at this time is 60 kW. At this time, the discharge amount gradually decreases until the target discharge amount is reached. Furthermore, when the remaining time in the second time zone decreases (time h), even if the generated power exceeds a predetermined threshold, discharging is started and discharging is performed continuously. In this way, the secondary battery 32 can be efficiently discharged in the second time zone.

  In the above embodiment, the discharge power is set to 60 kW and a constant value as shown in FIG. 15A. However, the present invention is not limited to this. For example, the power for discharging from the secondary battery 32 may be changed in proportion to the generated power. As shown in FIG. 15B, for example, with respect to the generated power from 50 kW to 100 kW, the discharge power changes within a range where the conversion efficiency of the converter 31 is good (60 kW to 100 kW: see FIG. 4). It is preferable to make it. As a result, when the difference between the generated power and the predetermined threshold is large, the discharge power increases, so the amount of power supplied in the power system increases, and the increase in the voltage state of the system power is promoted. On the other hand, when the difference between the generated power and the predetermined threshold is small, the discharge power is small. In this case, since the amount of power supply is not so large as compared with the above, the voltage state of the system power can be increased slowly without increasing rapidly. Thus, by changing the power discharged from the secondary battery 32 in proportion to the generated power, it is possible to efficiently suppress fluctuations in the voltage state of the system power.

  Note that the ratio between the discharged power of the secondary battery 32 and the generated power may be changed in accordance with the state of charge (SOC) of the secondary battery 32. As shown by the broken line in FIG. 15B, when the amount of charge of the secondary battery 32 is small (indicated by low SOC in FIG. 15B), the ratio of the discharged power and the generated power is reduced. The secondary battery 32 is not discharged so much. On the other hand, when the amount of charge of the secondary battery 32 is large (indicated by high SOC in FIG. 15B), by increasing the ratio between the discharged power and the generated power, the secondary battery 32 increases the amount of charge. Discharge.

  Moreover, you may change the electric power which discharges from the secondary battery 32 in steps according to generated electric power. The relationship between the generated power and the discharged power in this case is shown in FIG. Thereby, the discharge electric power in predetermined | prescribed generated electric power can be increased / decreased suitably. In the drawing, in the generated power in which the discharge power extends in the vertical direction, even if the generated power is the same, the discharge power can be appropriately increased or decreased. As a result, the discharge amount is increased or decreased in consideration of the remaining amount of discharge of the secondary battery 32 and the remaining time of the second time zone, so that the discharge is reliably completed within the second time zone. Can do. For example, when the amount of discharge is small with respect to the remaining time, it is possible to discharge quickly by increasing the discharge power for a predetermined generated power. Further, when the discharge amount is large with respect to the remaining time, the discharge time can be extended by reducing the discharge power and performing the discharge at a predetermined generated power. In this example as well, since the amount of discharge from the secondary battery 32 is increased or decreased according to the generated power, fluctuations in the voltage state of the system power can be efficiently suppressed as described above.

  Furthermore, in the above embodiment, the threshold value of the generated power when discharging from the secondary battery 32 is 40 kW, but is not limited thereto. The threshold value of the generated power may be changed according to the discharge state from the secondary battery 32 every predetermined time. In the present embodiment, the discharge state from the secondary battery 32 is detected every hour to determine whether or not a predetermined reference value (10%) has been reached. As shown in FIG. 16A, from 8 o'clock to 9 o'clock, the threshold value of the generated power is set to 40 kW, and discharging is performed when the threshold value is below the threshold. When one hour has passed, it is determined whether or not the amount of discharge from the secondary battery 32 has reached 10%. If it is determined that the discharge amount has reached, the control means 34 performs the next one hour (9:00 to 10:00). For, increase the threshold by 1 kW and set it to 41 kW (see FIG. 16B). Similarly, after 1 hour has passed, it is determined whether or not the discharge amount from the secondary battery 32 has reached 20%. If it has reached, the threshold is set to 42 kW, and the same is repeated thereafter. In addition, if the threshold value of generated electric power is continuously raised every hour, the threshold value is set to 54 kW at the maximum 21 times (see FIG. 16C). On the other hand, if the amount of discharge from the secondary battery 32 does not reach a predetermined reference value when one hour has elapsed, the set threshold value of the generated power is maintained as it is.

  In this way, when the discharge amount from the secondary battery 32 has reached a predetermined value after a predetermined time has elapsed, the threshold value is increased by a predetermined amount, so that the state where the generated power falls below the predetermined threshold value continues. Even in this case, it is possible to prevent the discharge from being completed during the second time period. If the discharge from the secondary battery 32 is completed in the middle of the second time period, the voltage state of the system power due to the discharge from the secondary battery 32 cannot be controlled thereafter. Therefore, the voltage state of the system power due to the discharge from the secondary battery 32 can be efficiently suppressed by preventing the discharge from being completed in the middle of the second time period.

  Further, the threshold value of the generated power may be lowered when the discharge amount from the secondary battery 32 reaches a predetermined value after a predetermined time has elapsed. In this case, as shown in FIG. 17A, the threshold value of the generated power is set to 45 kW from 8:00 to 9:00. After one hour has passed, it is determined whether or not the discharge amount from the secondary battery 32 has reached 10%. If it is determined that the discharge amount has reached, the threshold value is lowered by 1 kW and set to 44 kW as described above. If it is determined that the threshold has not been reached, the threshold is increased by 1 kW and set to 46 kW (see FIG. 17B). The same determination and threshold setting are repeated every hour. Thus, for example, when the discharge amount from the secondary battery 32 is large, the threshold value at 21 o'clock is 31 kW, and when the discharge amount is small, the threshold value at 21 o'clock is 54 kW (FIG. 17). (See (c)). By doing in this way, the discharge from a secondary battery can be completed reliably. If the discharge amount from the secondary battery is exactly 10% after 1 hour has elapsed from 8 o'clock, the threshold value is maintained, and similarly, when the discharge amount per hour is equal to the predetermined value. The threshold setting at that time may be maintained as it is.

  Thus, by changing the discharge power from the secondary battery and the threshold value of the generated power when discharging, the amount of discharge from the secondary battery 32 in the second time zone can be changed, The discharge can be performed over the entire second time period, and the discharge can be completed at the end of the second time period. In consideration of the relationship between the discharge time and the discharge amount shown in FIG. 13, when the remaining time until the end of the second time zone and the remaining discharge time coincide with each other, the control for continuously discharging is performed. By using in combination, the discharge can be completed more reliably at the end of the second time period.

  In addition, the threshold value of the generated power for discharging from the secondary battery 32 is not limited to the value set above, and can be set as appropriate. In addition, since the solar power generation 10A and the wind power generation 10B (see FIG. 1) can be used as natural energy in the second time zone, the predetermined threshold is set to be large at the beginning of the second time zone (for example, 90 kW). In addition, the control may be performed so that the threshold value is lowered when the discharge amount has not reached the predetermined reference value after the predetermined time has elapsed. Further, when the threshold value is raised or lowered, the amount of change may be changed instead of being changed for every fixed value. Thus, the timing and amount of discharge from the secondary battery 32 in the second time zone can be controlled by appropriately changing the threshold values of the discharge power and generated power. As a result, it is possible to efficiently suppress the change in the voltage state of the system power during the daytime.

  Further, as described above, the threshold value when discharging from the secondary battery 32 may be set based on the tendency (trend) of the generated power shown in FIG. As a result, since the threshold value used as a reference for whether or not to discharge from the secondary battery is set based on the tendency of the generated power at that time, the threshold value can be set appropriately and the discharge from the secondary battery can be performed. Thus, the voltage state of the system power can be controlled more efficiently.

  The embodiment of the present invention has been described above, but the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made without departing from the gist of the present invention. In addition, you may arrange | position the load leveling apparatus 30 of this invention in the some consumer 20 connected to the power transmission line 11 of the electric power grid | system 1. FIG.

DESCRIPTION OF SYMBOLS 1 Electric power system 10 Consumer 30 Load leveling apparatus 32 Secondary battery 33 Generated power detection means 34 Control apparatus

Claims (16)

A secondary battery that can be charged and discharged is installed at a customer of a power system to which power generation means using renewable energy is connected, and load balancing of power demand is performed by charging and discharging the secondary battery. A load leveling device,
Generated power detection means for detecting the generated power of the power generation means using the renewable energy;
Control means for controlling charging or discharging of the secondary battery,
The control means performs charging of the secondary battery in a first time zone in which less power is used by the consumer and when the generated power exceeds a predetermined threshold value. Load leveling device.   The load leveling device according to claim 1, wherein the power charged in the secondary battery is constant regardless of the generated power.   The load leveling apparatus according to claim 1, wherein power charged in the secondary battery is changed in proportion to the generated power.   The load leveling device according to claim 1, wherein the electric power charged in the secondary battery is changed stepwise according to the generated electric power.   The control means determines whether or not the state of charge of the secondary battery has reached a predetermined reference value every predetermined time in the first time zone, and determines that the predetermined reference value has not been reached. The threshold value is lowered by a predetermined amount in the case, and the threshold value is maintained when it is determined that the predetermined reference value has been reached. Load leveling device.   The control means determines whether or not the state of charge of the secondary battery has reached a predetermined reference value every predetermined time in the first time zone, and determines that the predetermined reference value has been reached. The threshold value is increased by a predetermined amount in the case, and the threshold value is decreased by a predetermined amount when it is determined that the predetermined reference value has not been reached. The load leveling device described in 1.   The load leveling apparatus according to any one of claims 1 to 6, wherein the predetermined threshold is set based on a tendency of the generated power grasped in advance. The first time zone is set longer than the charging time required to charge the secondary battery with a target charge amount,
The control means obtains a charge remaining amount until the charging is completed from a charge amount charged to the secondary battery at a predetermined time and the target charge amount, and obtains a charge amount and charge of the secondary battery obtained in advance. Based on the relationship with time, the remaining charge time required to charge the remaining charge is obtained, and the remaining time from the predetermined time point until the end of the first time zone and the remaining charge time are calculated. 8. The battery according to claim 1, wherein when the remaining time coincides with the remaining charging time, the secondary battery is continuously charged during the remaining time. Load fluctuation leveling device. A secondary battery that can be charged and discharged is installed at a customer of a power system to which power generation means using renewable energy is connected, and load balancing of power demand is performed by charging and discharging the secondary battery. A load leveling device,
Generated power detection means for detecting the generated power of the power generation means using the renewable energy;
Control means for controlling charging or discharging of the secondary battery,
The control means discharges the secondary battery in a second time zone in which a large amount of power is used by the consumer and the generated power falls below a predetermined threshold. Leveling device.   The load leveling apparatus according to claim 9, wherein the electric power discharged from the secondary battery is constant regardless of the generated electric power.   The load leveling device according to claim 9, wherein power discharged from the secondary battery is changed in proportion to the generated power.   The load leveling apparatus according to claim 9, wherein the electric power discharged from the secondary battery is changed stepwise according to the generated electric power.   The control means determines whether or not the discharge state of the secondary battery has reached a predetermined reference value every predetermined time in the second time zone, and determines that the predetermined reference value has not been reached. The threshold value is increased by a predetermined amount in a case, and the threshold value is maintained when it is determined that the predetermined reference value has been reached. Load leveling device.   The control means determines whether or not the discharge state of the secondary battery has reached a predetermined reference value every predetermined time in the second time zone, and determines that the predetermined reference value has been reached. The threshold value is lowered by a predetermined amount in the case, and the threshold value is raised by a predetermined amount when it is determined that the predetermined reference value has not been reached. The load leveling device described in 1.   The load leveling apparatus according to any one of claims 9 to 14, wherein the predetermined threshold is set based on a tendency of the generated power grasped in advance. The second time zone is set longer than the discharge time necessary to discharge the target discharge amount from the secondary battery,
The control means obtains a remaining amount of discharge until the discharge is completed from a discharge amount discharged from the secondary battery at a predetermined time and the target discharge amount, and calculates the discharge amount and discharge of the secondary battery obtained in advance. Based on the relationship with time, the remaining discharge time required to discharge the remaining discharge is obtained, and the remaining time from the predetermined time point until the end of the second time zone and the remaining discharge time are calculated. 16. The discharge according to claim 9, wherein when the remaining time coincides with the remaining discharge time, the secondary battery is continuously discharged during the remaining time. Load fluctuation leveling device.

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