JP2016041002A - Charging/discharging control device and charging/discharging control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce variation in power storage amounts of respective cells of a power storage device while smoothing output fluctuation.SOLUTION: A charging/discharging control device 10 comprises: a power generation amount detecting section 11 that detects a power generation amount Pg of a renewable energy generator 3; a power storage amount detecting section 12 that detects a power storage amount Cb of a power storage device 5 constituted of a plurality of cells; a target amount setting section 13 that sets a target output amount Pt according to the power generation amount Pg and the power storage amount Cb; and a charging/discharging amount instructing section 14 that instructs the charging/discharging amount of the power storage device 5 according to the power generation amount Pg and the target output amount Pt. The target amount setting section 13, when the power storage amount Cb increases, sets the target output amount Pt to a charge-side target output amount Ptuntil the power storage amount Cb reaches a first power storage amount C1 larger than a half of a power storage capacity of the power storage device 5; and after the power storage amount Cb reaches the first power storage amount C1, sets the target output amount Pt to a discharge-side target output amount Pt.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a charge / discharge control device and a charge / discharge control method.

  In recent years, a renewable energy power generation system using renewable energy such as sunlight and wind power has attracted attention. In such a renewable energy power generation system, the amount of power generation may vary depending on the weather of the day. When a renewable energy power generation system is connected to a commercial grid, fluctuations in the output of the renewable energy power generation system can disrupt the balance of supply and demand in the grid, possibly destabilizing the grid. For this reason, the renewable energy power generation system is required to smooth the output fluctuation.

  When using a power storage device, if the amount of power generated by the renewable energy power generation system exceeds the output target value, surplus power is charged into the power storage device, and if it is below the output target value, insufficient power is discharged from the power storage device. Is known to smooth output fluctuations. Since the storage capacity that can be charged / discharged is determined in advance in the power storage device, further charging is performed from a fully charged state (end-of-charge state), and further discharging is performed from a state where the amount of stored power is insufficient (end-of-discharge state). I can't. Therefore, when the power storage device is in a charged / discharged state, the function of smoothing output fluctuations may stop. For this reason, it is necessary to control charging / discharging of the power storage device so as to avoid the power storage device from being charged and discharged.

  For example, Patent Literature 1 describes a power supply system including a power storage unit (power storage device) that stores power, a power adjustment unit that performs charge / discharge power adjustment of the power storage unit, and a control unit. In this power supply system, as the amount of power stored in the power storage device increases, the output target value is set to be increased stepwise to prevent the power storage device from entering the end-of-discharge state and the end-of-charge state.

JP 2001-327080 A

  By the way, when the electrical storage apparatus comprised from several cells, such as a lithium ion battery, is used, dispersion | variation arises by the charge / discharge of an electrical storage apparatus being repeated. If the amount of electricity stored in each cell varies, the amount of electricity that can be used as the entire power storage device is limited by the cell with the smallest amount of electricity stored in the cells of the power storage device. Therefore, during operation, it is required to perform balance charging that equalizes the amount of electricity stored in each cell.

  However, in the power supply system described in Patent Document 1, the output target value of the power supply system is set so that the power storage device does not enter the end-of-discharge state and end-of-charge state. For this reason, when a power storage device including a plurality of cells is used as the power storage device, once a variation occurs in the power storage amount of each cell of the power storage device during operation, the power storage amount of each cell can be made uniform. Therefore, the power storage device may not be used efficiently.

  The present invention provides a charge / discharge control device and a charge / discharge control method capable of reducing variations in the amount of electricity stored in each cell of the power storage device while smoothing output fluctuations.

  A charge / discharge control device according to one embodiment of the present invention is a charge / discharge control device that controls charge / discharge of a power storage device in a power generation system including a renewable energy power generation device and a power storage device including a plurality of cells. The charge / discharge control device includes a power generation amount detection unit that detects a power generation amount of the renewable energy power generation device, a power storage amount detection unit that detects a power storage amount of the power storage device, and a power generation amount detected by the power generation amount detection unit, A target value setting unit that sets an output target value of the power generation system in accordance with the power storage amount detected by the power storage amount detection unit, a power generation amount detected by the power generation amount detection unit, and a target value setting unit A charge / discharge amount instruction unit for instructing a charge / discharge amount of the power storage device according to the output target value. The target value setting unit increases the storage amount until the storage amount reaches a first storage amount that is larger than half of the storage capacity of the storage device when the storage amount detected by the storage amount detection unit is increasing. The output target value is set as the charge-side output target value to be set, and after the storage amount reaches the first storage amount, the output target value is set as the discharge-side output target value that decreases the storage amount.

  According to the charge / discharge control device, when the storage amount is increasing, the storage amount of the storage device is reduced until the storage amount of the storage device reaches the first storage amount that is larger than half of the storage capacity of the storage device. The output target value of the power generation system is set to the charging side output target value to be increased. For this reason, even if the power storage amount of the power storage device exceeds half of the power storage capacity, the power storage device continues to be charged, and the power storage device approaches the end-of-charge state. Thereby, variation in the amount of electricity stored in each cell of the power storage device is reduced, and the power storage device can be used efficiently. In addition, after the amount of power stored in the power storage device reaches the first power storage amount, the output target value of the power generation system is set to the discharge-side output target value that decreases the amount of power stored in the power storage device. For this reason, when the power storage amount of the power storage device reaches the first power storage amount, the power storage device is discharged, and the power storage device is suppressed from being charged beyond the end-of-charge state. Thereby, it becomes possible to continue smoothing of output fluctuations. As a result, it is possible to reduce variations in the amount of power stored in each cell of the power storage device while smoothing output fluctuations.

  The target value setting unit, when the storage amount detected by the storage amount detection unit is decreasing, until the storage amount reaches a second storage amount that is less than half of the storage capacity of the storage device. The output target value may be set as the value, and the output target value may be set as the charge-side output target value after the amount of power storage reaches the second power storage amount. In this case, when the storage amount is decreasing, the discharge-side output target for decreasing the storage amount of the storage device until the storage amount of the storage device reaches the second storage amount that is smaller than half of the storage capacity of the storage device The output target value of the power generation system is set as the value. For this reason, even if the amount of power stored in the power storage device becomes smaller than half of the power storage capacity, the power storage device continues to be discharged, and the power storage device approaches the end-of-discharge state. In addition, after the amount of power stored in the power storage device reaches the second amount of power storage, the output target value of the power generation system is set to the charge-side output target value that increases the amount of power stored in the power storage device. For this reason, when the power storage amount of the power storage device reaches the second power storage amount, the power storage device is charged, and the power storage device is further prevented from being discharged from the end-of-discharge state. Thereby, it becomes possible to continue smoothing of output fluctuations.

  The target value setting unit detects the moving average of the power generation amount detected by the power generation amount detection unit, the amplitude of the power generation amount detected by the power generation amount detection unit, and the power storage amount detection unit The output target value is calculated by correcting the moving average calculated by the moving average calculation unit with the correction value set by the correction value setting unit. And a target value calculation unit. The correction value setting unit sets a positive bias value determined according to the amplitude of the power generation amount or a negative bias value determined according to the amplitude of the power generation amount as the correction value, and the target value calculation unit calculates the moving average The output target value may be calculated by adding the correction value set by the correction value setting unit to the moving average calculated by the calculation unit. In this case, by setting a positive bias value determined according to the amplitude of the power generation amount to the moving average of the power generation amount as the output target value, it is possible to increase the possibility that the power generation amount will fall below the output target value. it can. For this reason, the power storage amount of the power storage device can be reduced, that is, the power storage device can be discharged. Further, by setting a value obtained by adding a negative bias value determined according to the amplitude of the power generation amount to the moving average of the power generation amount as the output target value, the possibility that the power generation amount exceeds the output target value can be increased. . For this reason, the power storage amount of the power storage device can be increased, that is, the power storage device can be charged.

  When changing the correction value from the negative bias value to the positive bias value, the correction value setting unit gradually increases the negative bias value so that the positive bias value is obtained at a predetermined time. When the correction value is changed and the correction value is changed from a positive bias value to a negative bias value, the positive bias value is gradually decreased so that the negative bias value is obtained at a predetermined time. The correction value may be changed. In this case, the correction value can be changed slowly, and the output target value can be prevented from changing suddenly. For this reason, it is possible to avoid a sudden change in the output and to stabilize the system.

  The correction value setting unit calculates a bias value according to the amplitude of the power generation amount detected by the power generation amount detection unit, and a bias for determining a bias coefficient according to the power storage amount detected by the power storage amount detection unit A coefficient determination unit and a correction value calculation unit that calculates a correction value by multiplying the bias value calculated by the bias calculation unit and the bias coefficient determined by the bias coefficient determination unit may be provided. In this case, a bias value is calculated according to the amplitude of the power generation amount, a bias coefficient is calculated according to the power storage amount of the power storage device, and a correction value is calculated by multiplying the bias value and the bias coefficient. For this reason, since the influence on the correction value due to the change in the amplitude of the power generation amount and the influence on the correction value due to the change in the power storage amount of the power storage device can be separated, calculation of the correction value is simplified. Can be realized.

  The target value setting unit sets the output target value so that the power storage amount approaches half of the power storage capacity of the power storage device when the power generation amount detected by the power generation amount detection unit is greater than or equal to a predetermined amplitude. May be. When the amplitude of the power generation amount is greater than or equal to a predetermined amplitude, the power generation amount of the renewable energy power generation device may be in an unstable state. For this reason, charging / discharging of an electrical storage apparatus is performed frequently. In such a case, it is possible to suppress the charge / discharge amount of the power storage device from exceeding the upper limit of the performance of the power storage device by setting the power storage amount to a state close to half of the power storage capacity of the power storage device.

  The target value setting unit sets the output target value so that the power storage amount approaches half of the power storage capacity of the power storage device when the frequency of the power generation detected by the power generation amount detection unit is equal to or higher than a predetermined frequency. May be. When the frequency of the power generation amount is equal to or higher than a predetermined frequency, the power generation amount of the renewable energy power generation apparatus may be in an unstable state. For this reason, charging / discharging of an electrical storage apparatus is performed frequently. In such a case, it is possible to suppress the charge / discharge amount of the power storage device from exceeding the upper limit of the performance of the power storage device by setting the power storage amount to a state close to half the power storage capacity of the power storage device.

  A charge / discharge control method according to another aspect of the present invention is performed by a charge / discharge control device that controls charge / discharge of a power storage device in a power generation system including a renewable energy power generation device and a power storage device including a plurality of cells. This is a charge / discharge control method. The charge / discharge control method includes a power generation amount detection step for detecting a power generation amount of the renewable energy power generation device, a power storage amount detection step for detecting a power storage amount of the power storage device, and a power generation amount detected in the power generation amount detection step, The target value setting step for setting the output target value of the power generation system according to the power storage amount detected in the power storage amount detection step, the power generation amount detected in the power generation amount detection step, and the target value setting step A charge / discharge amount instructing step for instructing the charge / discharge amount of the power storage device according to the output target value. In the target value setting step, when the storage amount detected in the storage amount detection step is increasing, the storage amount is increased until the storage amount reaches a first storage amount that is larger than half of the storage capacity of the storage device. The output target value is set so that the power storage amount reaches the first power storage amount, and the output target value is set so that the power storage amount decreases.

  According to this charge / discharge control method, when the storage amount is increasing, the storage amount of the storage device is reduced until the storage amount of the storage device reaches the first storage amount that is larger than half of the storage capacity of the storage device. The output target value of the power generation system is set to the charging side output target value to be increased. For this reason, even if the power storage amount of the power storage device exceeds half of the power storage capacity, the power storage device continues to be charged, and the power storage device approaches the end-of-charge state. Thereby, variation in the amount of electricity stored in each cell of the power storage device is reduced, and the power storage device can be used efficiently. In addition, after the amount of power stored in the power storage device reaches the first power storage amount, the output target value of the power generation system is set to the discharge-side output target value that decreases the amount of power stored in the power storage device. For this reason, when the power storage amount of the power storage device reaches the first power storage amount, the power storage device is discharged, and the power storage device is suppressed from being charged beyond the end-of-charge state. Thereby, it becomes possible to continue smoothing of output fluctuations. As a result, it is possible to reduce variations in the amount of power stored in each cell of the power storage device while smoothing output fluctuations.

  ADVANTAGE OF THE INVENTION According to this invention, the dispersion | variation in the electrical storage amount of each cell of an electrical storage apparatus can be reduced, smoothing an output fluctuation.

1 is a diagram schematically showing a configuration of a power generation system including a charge / discharge control device according to an embodiment. It is a functional block diagram of the charging / discharging control apparatus of FIG. It is a figure which shows an example of the relationship between SOC and a bias coefficient. It is a figure which shows an example of transition of electric power generation amount, a moving average, and an output target value. It is a flowchart which shows the charging / discharging control method performed by the charging / discharging control apparatus of FIG. It is a flowchart which shows the correction value setting process of FIG. It is a figure which shows the simulation result of transition of electric power generation amount, a moving average, and an output target value. It is a figure which shows the simulation result of transition of SOC.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant descriptions are omitted.

  FIG. 1 is a diagram schematically illustrating a configuration of a power generation system including a charge / discharge control device according to an embodiment. As shown in FIG. 1, a power generation system 1 is connected to a commercial power system 2 and supplies power (hereinafter referred to as “output Ps”) to a power supply target (not shown) through interconnection with the commercial power system 2. It is a supply system. The power generation system 1 has a function of smoothing fluctuations in the output Ps (hereinafter, simply referred to as “smoothing of the output Ps”). The power generation system 1 is, for example, a renewable energy power plant. The power generation system 1 includes a renewable energy power generation device 3, a power conditioner (PCS) 4, a power storage device 5, a bidirectional converter 6, a wattmeter 7, and a charge / discharge control device 10.

  The renewable energy power generation device 3 is a device that generates power using renewable energy. In the renewable energy power generation device 3, the output, that is, the power generation amount Pg can vary. The renewable energy power generation device 3 is, for example, a solar power generator (PV), a wind power generator, or the like. The renewable energy power generation device 3 outputs the power generation amount Pg via the power conditioner 4. The power conditioner 4 is a device that converts DC power from the renewable energy power generation device 3 into AC power.

  The power storage device 5 is a power storage device including a plurality of cells. In the power storage device 5, the charge amount of each cell may vary due to repeated charge and discharge. The power storage device 5 is, for example, a lithium ion battery (LiB). In the power storage device 5, if there is a variation in the power storage amount of each cell, the power storage amount usable as the power storage device 5 as a whole is limited by the cell having the smallest power storage amount among the cells of the power storage device 5. The power storage device 5 is used for smoothing the output Ps of the power generation system 1. Specifically, when the power generation amount Pg of the renewable energy power generation device 3 exceeds the output target value Pt of the power generation system 1, the surplus power Pc is stored in the power storage device 5, and the renewable energy power generation device 3 When the power generation amount Pg falls below the output target value Pt of the power generation system 1, the shortage power Pc is supplemented by the power stored in the power storage device 5.

  The bidirectional converter 6 is a device that switches between an operation of storing the electric power generated by the renewable energy power generation device 3 in the power storage device 5 and an operation of supplying the electric power stored in the power storage device 5 to the outside. The bidirectional converter 6 is, for example, an AC / DC inverter. Bidirectional converter 6 receives a charge / discharge command that instructs charging or discharging of power storage device 5 from charge / discharge control device 10. Bidirectional converter 6 stores a part of power generation amount Pg of renewable energy power generation device 3 in power storage device 5 or a part of the power stored in power storage device 5 in accordance with the received charge / discharge command. Is supplied to the outside.

  The wattmeter 7 is a device that measures the power generation amount Pg of the renewable energy power generation device 3. The wattmeter 7 continuously measures, for example, the power generation amount Pg of the renewable energy power generation device 3. The wattmeter 7 transmits the measured power generation amount Pg to the charge / discharge control device 10.

  The charging / discharging control device 10 is a device that controls charging / discharging of the power storage device 5, and includes, for example, an information processing device. The charge / discharge control device 10 is physically composed of one or a plurality of CPUs (Central Processing Units), a main storage device such as a RAM (Random Access Memory) and a ROM (Read Only Memory), an auxiliary storage device such as a hard disk device, and the like. A computer including hardware such as a communication device which is a data transmission / reception device is configured. Each function to be described later of the charge / discharge control device 10 causes each hardware to operate under the control of the CPU by causing the hardware such as the CPU and RAM to read one or more predetermined computer programs. This is realized by reading and writing data in the auxiliary storage device.

  FIG. 2 is a functional block diagram of the charge / discharge control device 10. As shown in FIG. 2, the charge / discharge control device 10 functionally includes a power generation amount detection unit 11, a storage amount detection unit 12, a target value setting unit 13, and a charge / discharge amount instruction unit 14. Prepare.

  The power generation amount detection unit 11 functions as a power generation amount detection unit that detects the power generation amount Pg of the renewable energy power generation device 3. The power generation amount detection unit 11 receives the power generation amount Pg from the wattmeter 7 and transmits the received power generation amount Pg to the target value setting unit 13 and the charge / discharge amount instruction unit 14.

  The storage amount detection unit 12 functions as a storage amount detection unit that detects the storage amount Cb of the storage device 5. For example, the storage amount detection unit 12 detects a state of charge (SOC) as the storage amount Cb. The SOC is stored in the power storage device 5 with respect to the power storage capacity, which is the maximum capacity that can be stored in the power storage device 5, with the end state of charge of the power storage device 5 being 100% and the end state of discharge of the power storage device 5 being 0%. Indicates the percentage of electricity. In addition, the detection of the charged amount Cb such as SOC is performed by a known means. The power storage amount detection unit 12 transmits the detected power storage amount Cb to the target value setting unit 13.

  The target value setting unit 13 sets the output target value Pt of the power generation system 1 according to the power generation amount Pg detected by the power generation amount detection unit 11 and the power storage amount Cb detected by the power storage amount detection unit 12. It functions as a value setting means. The target value setting unit 13 includes a moving average calculation unit 15, a correction value setting unit 16, and a target value calculation unit 17.

  The moving average calculation unit 15 functions as a moving average calculation unit that calculates a moving average Pave of the power generation amount Pg detected by the power generation amount detection unit 11. The moving average calculator 15 calculates the moving average Pave of the power generation amount Pg in a predetermined period. The calculation target period of the moving average Pave is, for example, a period from 30 minutes before the time for calculating the moving average Pave to the time for calculating the moving average Pave. The moving average calculator 15 repeatedly calculates the moving average Pave of the power generation amount Pg at a predetermined time interval. The calculation interval of the moving average Pave is, for example, about 1 minute. The moving average calculation unit 15 transmits the calculated moving average Pave to the correction value setting unit 16 and the target value calculation unit 17.

  The correction value setting unit 16 sets a correction value M according to the amplitude of the power generation amount Pg detected by the power generation amount detection unit 11 and the power storage amount Cb detected by the power storage amount detection unit 12. Function as. The correction value setting unit 16 includes a bias calculation unit 18, a bias coefficient determination unit 19, and a correction value calculation unit 20.

  The bias calculation unit 18 functions as a bias calculation unit that calculates a bias value corresponding to the amplitude of the power generation amount Pg detected by the power generation amount detection unit 11. For example, the bias calculation unit 18 calculates the difference between the moving average Pave and the power generation amount Pg in a predetermined period, and sets half of the maximum value and the minimum value as the amplitude of the power generation amount Pg. The calculation target period of the amplitude of the power generation amount Pg is, for example, about the same as the calculation target period of the moving average Pave, that is, from 30 minutes before the time of calculating the amplitude of the power generation amount Pg to the time of calculating the amplitude of the power generation amount Pg. Is the period. The bias calculation unit 18 repeatedly calculates the amplitude of the power generation amount Pg at a predetermined time interval. The calculation interval of the amplitude of the power generation amount Pg is about the same as the time interval of the moving average Pave. For example, the bias calculation unit 18 may set the amplitude of the power generation amount Pg as the bias value α, and may further set a value smaller than the amplitude of the power generation amount Pg as the bias value α in consideration of the performance of the power storage device 5. In other words, the bias value α is calculated according to the maximum value and the minimum value of the relative displacement of the power generation amount Pg with respect to the moving average Pave in each period. The bias calculation unit 18 further calculates a bias value β smaller than the bias value α. The bias value β is calculated according to the charge / discharge capability of the power storage device 5.

  The bias calculation unit 18 determines whether or not the amplitude of the power generation amount Pg is greater than or equal to a predetermined threshold amplitude Ath. For example, the threshold amplitude Ath is obtained by measuring the amplitude of the past power generation amount Pg based on the actual value of the power generation amount Pg at the time of cloudy weather in the same season in the past, and adding a coefficient (for example, 0.8) to the average value of the measured amplitude. The value multiplied by. Further, the bias calculation unit 18 determines whether or not the frequency of the power generation amount Pg is equal to or higher than a predetermined threshold frequency Fth. The threshold frequency Fth is obtained by measuring the frequency of the past power generation amount Pg based on the actual value of the power generation amount Pg at the time of cloudy weather in the same season in the past, and a coefficient (for example, 0.8) on the average value of the measured frequencies. The value multiplied by. Further, the bias calculation unit 18 determines whether or not the absolute value of the difference between the charged amount Cb and the charged capacity of the power storage device 5 is greater than a predetermined value x. Here, the value x is about 5%, for example.

  When the bias calculation unit 18 determines that the amplitude of the power generation amount Pg is less than the threshold amplitude Ath and the frequency of the power generation amount Pg is less than the threshold frequency Fth, the bias is calculated so that the bias coefficient γ is determined by hysteresis. The coefficient determination unit 19 is instructed and the bias value α is transmitted to the correction value calculation unit 20. When the bias calculation unit 18 determines that the amplitude of the power generation amount Pg is greater than or equal to the threshold amplitude Ath, or when it determines that the frequency of the power generation amount Pg is greater than or equal to the threshold frequency Fth, the power storage amount Cb is equal to the power storage device 5. The bias coefficient determination unit 19 is instructed to determine a bias coefficient γ that approaches half of the storage capacity of

  When the bias calculation unit 18 determines that the amplitude of the power generation amount Pg is greater than or equal to the threshold amplitude Ath and that the absolute value of the difference between the storage amount Cb and half of the storage capacity of the storage device 5 is greater than the value x, The bias value β is transmitted to the correction value calculation unit 20. Further, when the bias calculation unit 18 determines that the frequency of the power generation amount Pg is equal to or higher than the threshold frequency Fth and that the absolute value of the difference between the power storage amount Cb and half of the power storage capacity of the power storage device 5 is greater than the value x. In addition, the bias value β is transmitted to the correction value calculation unit 20. When the bias calculation unit 18 determines that the amplitude of the power generation amount Pg is equal to or greater than the threshold amplitude Ath and that the absolute value of the difference between the power storage amount Cb and half of the power storage capacity of the power storage device 5 is equal to or less than the value x. The bias value is set to zero and transmitted to the correction value calculation unit 20. Further, the bias calculation unit 18 determines that the frequency of the power generation amount Pg is equal to or higher than the threshold frequency Fth, and the absolute value of the difference between the power storage amount Cb and half of the power storage capacity of the power storage device 5 is equal to or less than the value x. In this case, the bias value is set to zero and transmitted to the correction value calculation unit 20.

  The bias coefficient determination unit 19 functions as a bias coefficient determination unit that determines a bias coefficient γ according to the storage amount Cb detected by the storage amount detection unit 12. This bias coefficient γ takes a value of −1 or more and +1 or less. First, the process for determining the bias coefficient γ by hysteresis will be described. The bias coefficient determination unit 19 sets the bias coefficient γ to −1 until the charged amount Cb reaches the first charged amount C1, and the charged amount Cb reaches the first charged amount C1 in a state where the charged amount Cb is increasing. After that, the bias coefficient γ is set to +1. The bias coefficient determining unit 19 sets the bias coefficient γ to +1 until the charged amount Cb reaches the second charged amount C2 in a state where the charged amount Cb is decreasing, and after the charged amount Cb reaches the second charged amount C2. The bias coefficient γ is -1.

  That is, when the power storage device 5 is charged, the bias coefficient determination unit 19 sets the bias coefficient γ to −1 when the power storage amount Cb is equal to or less than the first power storage amount C1, and the power storage amount Cb is higher than the first power storage amount C1. If it is larger, the bias coefficient γ is set to +1. The bias coefficient determination unit 19 sets the bias coefficient γ to +1 when the power storage amount Cb is equal to or greater than the second power storage amount C2 when the power storage device 5 is discharged, and when the power storage amount Cb is smaller than the second power storage amount C2. The bias coefficient γ is set to -1. Thus, the bias coefficient γ is determined by a function system of the charged amount Cb having hysteresis.

  The first power storage amount C1 is larger than half the power storage capacity of the power storage device 5 and smaller than the power storage capacity of the power storage device 5. The first power storage amount C1 is set so that the power storage device 5 approaches the end-of-charge state when the power storage amount Cb changes from increasing to decreasing when the bias coefficient γ is switched from −1 to +1. The first power storage amount C1 is, for example, about 80% of the power storage capacity of the power storage device 5. The second power storage amount C2 is smaller than half of the power storage capacity of the power storage device 5 and larger than zero. The second power storage amount C2 is set so that the power storage device 5 approaches the end-of-discharge state when the power storage amount Cb changes from decreasing to increasing when the bias coefficient γ is switched from +1 to −1. The second power storage amount C2 is about 40% of the power storage capacity of the power storage device 5, for example.

  When the power storage device 5 is charged, the bias coefficient determination unit 19 gradually increases the bias coefficient γ from −1 to +1 at a predetermined transition time in response to the storage amount Cb reaching the first storage amount C1. May increase. The bias coefficient determination unit 19 gradually increases the bias coefficient γ from +1 to −1 at a predetermined transition time in response to the charged amount Cb reaching the second charged amount C2 when the power storage device 5 is discharged. May decrease. The change rate of the output Ps varies depending on the transition time. Since the upper limit of the rate of change of the output Ps is a required value of the commercial power system 2, the transition time is adjusted so as not to exceed the upper limit of the rate of change of the output Ps. Then, the bias coefficient determination unit 19 transmits the bias coefficient γ to the correction value calculation unit 20.

  FIG. 3 is a diagram illustrating an example of the relationship between the SOC and the bias coefficient. From the point where the SOC is the first power storage amount C1 and the bias coefficient γ is −1, the line segment extending in the direction in which the SOC and the bias coefficient γ increase increases the SOC of the power storage device 5 to the first power storage amount C1. This means that the bias coefficient γ gradually increases from −1 to +1 at a predetermined transition time regardless of the SOC. In addition, a line segment extending from the point where the SOC is the second storage amount C2 and the bias coefficient γ is +1 to the direction in which the SOC and the bias coefficient γ decrease decreases the SOC of the power storage device 5 and the second storage amount C2 This means that the bias coefficient γ gradually decreases from +1 to −1 at a predetermined transition time regardless of the SOC.

  Next, a process for determining the bias coefficient γ so that the charged amount Cb approaches half of the charged capacity of the power storage device 5 will be described. When the bias calculation unit 18 determines that the amplitude of the power generation amount Pg is greater than or equal to the threshold amplitude Ath and that the absolute value of the difference between the power storage amount Cb and half of the power storage capacity of the power storage device 5 is greater than the value x. The bias coefficient determination unit 19 determines the bias coefficient γ so that the charged amount Cb approaches half of the charged capacity of the power storage device 5. Further, the bias calculation unit 18 determines that the frequency of the power generation amount Pg is equal to or higher than the threshold frequency Fth and that the absolute value of the difference between the power storage amount Cb and half of the power storage capacity of the power storage device 5 is greater than the value x. In this case, the bias coefficient determination unit 19 determines the bias coefficient γ so that the charged amount Cb approaches the half of the charged capacity of the power storage device 5. Also in this case, the bias coefficient γ is adjusted so as not to exceed the upper limit of the rate of change of the output Ps requested from the commercial power system 2. For example, the bias coefficient determination unit 19 sets the bias coefficient γ to +1 when the charged amount Cb is larger than half of the charged capacity of the power storage device 5, and the charged amount Cb is smaller than half of the charged capacity of the power storage device 5. If it is smaller, the bias coefficient γ is set to -1. Then, the bias coefficient determination unit 19 transmits the bias coefficient γ to the correction value calculation unit 20.

  The correction value calculation unit 20 functions as a correction value calculation unit that calculates the correction value M according to the bias value calculated by the bias calculation unit 18 and the bias coefficient γ determined by the bias coefficient determination unit 19. The correction value calculation unit 20 includes, for example, a multiplier, and calculates a positive bias value or a negative bias value obtained by multiplying the bias value and the bias coefficient γ as the correction value M. The correction value calculation unit 20 transmits the calculated correction value M to the target value calculation unit 17.

  As described above, the correction value setting unit 16 including the bias calculation unit 18, the bias coefficient determination unit 19, and the correction value calculation unit 20 has a positive bias value or a power generation amount Pg determined according to the amplitude of the power generation amount Pg. A negative bias value determined according to the amplitude of is set to the correction value M. Further, when the correction value M is changed from the negative bias value to the positive bias value, the correction value setting unit 16 gradually increases the negative bias value to increase the positive bias at a predetermined transition time. The correction value M may be changed to be a value. When changing the correction value M from a positive bias value to a negative bias value, the correction value setting unit 16 gradually decreases the positive bias value, thereby reducing the negative bias value at a predetermined transition time. The correction value M may be changed so that

The target value calculation unit 17 serves as target value calculation means for calculating the output target value Pt by correcting the moving average Pave calculated by the moving average calculation unit 15 with the correction value M set by the correction value setting unit 16. Function. The target value calculation unit 17 is configured by, for example, an adder, and calculates the output target value Pt by adding the correction value M to the moving average Pave. The target value calculation unit 17 transmits the calculated output target value Pt to the charge / discharge amount instruction unit 14. Here, the output target value Pt obtained by subtracting the bias value α from the moving average Pave in each period is set as the charging side output target value Pt _c, and the bias value α is added to the moving average Pave in each period. the output target value Pt, which is a discharge side output target value Pt _d.

As described above, the target value setting unit 13 including the moving average calculation unit 15, the correction value setting unit 16, and the target value calculation unit 17 is configured such that the storage amount Cb is the first storage amount in the state where the storage amount Cb is increasing. until a quantity C1 is set to the charging-side output target value Pt _c output target value Pt so as to increase the storage amount Cb. The target value setting unit 13 sets the output target value Pt to the discharge side output target so as to decrease the charged amount Cb after the charged amount Cb reaches the first charged amount C1 in a state where the charged amount Cb is increasing. Set to the value Pt _d . The target value setting unit 13 sets the output target value Pt to the discharge side output target value so as to decrease the charged amount Cb until the charged amount Cb reaches the second charged amount C2 in a state where the charged amount Cb is decreasing. Set to Pt _d . The target value setting unit 13 sets the output target value Pt to the charge side output target so as to increase the charged amount Cb after the charged amount Cb reaches the second charged amount C2 in a state where the charged amount Cb is decreasing. Set to the value Pt _c .

  The target value setting unit 13 sets the output target value Pt so that the power storage amount Cb approaches half the power storage capacity of the power storage device 5 when the amplitude of the power generation amount Pg is equal to or greater than the threshold amplitude Ath. The target value setting unit 13 sets the output target value Pt so that the power storage amount Cb approaches half the power storage capacity of the power storage device 5 when the frequency component of the power generation amount Pg includes a component equal to or higher than the threshold frequency Fth.

FIG. 4 is a diagram illustrating an example of changes in the power generation amount Pg, the moving average Pave, and the output target value Pt. As shown in FIG. 4, since the power generation amount Pg varies with time, the moving average Pave of the power generation amount Pg also varies with time. The charge side output target value Pt _c is a value obtained by subtracting the bias value α from the moving average Pave in each period, and the discharge side output target value Pt _d is a value obtained by adding the bias value α to the moving average Pave in each period. is there. Since the power generation amount Pg is likely to be larger than the charge side output target value Pt _c , when the output target value Pt is set to the charge side output target value Pt _c , the power storage device 5 is charged and the power storage amount Cb increases. . On the other hand, since the power generation amount Pg is likely to be smaller than the discharge-side output target value Pt _d, when the output target value Pt and the discharge-side output target value Pt _d, the battery 5 is discharged, the storage amount Cb is Decrease.

  The charge / discharge amount instruction unit 14 instructs the charge / discharge amount of the power storage device 5 according to the power generation amount Pg detected by the power generation amount detection unit 11 and the output target value Pt set by the target value setting unit 13. It functions as a charge / discharge amount instruction means. The charge / discharge amount instruction unit 14 is constituted by, for example, a subtracter, and calculates the charge / discharge amount by subtracting the power generation amount Pg from the output target value Pt. That is, when the power generation amount Pg is larger than the output target value Pt, the output Ps of the power generation system 1 is brought close to the output target value Pt by charging the power storage device 5. On the other hand, when the power generation amount Pg is smaller than the output target value Pt, the output Ps of the power generation system 1 is brought close to the output target value Pt by discharging the power storage device 5. The charge / discharge amount instruction unit 14 transmits a charge / discharge command including the calculated charge / discharge amount to the bidirectional converter 6.

  Next, a charge / discharge control method executed by the charge / discharge control apparatus 10 will be described with reference to FIG. FIG. 5 is a flowchart showing a charge / discharge control method executed by the charge / discharge control apparatus 10. A series of processes shown in FIG. 5 are periodically executed while the charge / discharge control device 10 is activated, for example.

  First, the power generation amount detection unit 11 detects the power generation amount Pg of the renewable energy power generation device 3 (step S01, power generation amount detection step). Specifically, the power generation amount detection unit 11 receives the power generation amount Pg from the wattmeter 7 and transmits the received power generation amount Pg to the target value setting unit 13 and the charge / discharge amount instruction unit 14. The storage amount detection unit 12 detects the storage amount Cb of the storage device 5 (step S02, storage amount detection step). Then, the storage amount detection unit 12 transmits the detected storage amount Cb to the target value setting unit 13.

  Subsequently, the moving average calculation unit 15 calculates a moving average Pave of the power generation amount Pg detected in step S01 (step S03, moving average calculation step). The moving average calculation unit 15 repeatedly calculates the moving average Pave of the power generation amount Pg in a predetermined period at predetermined time intervals. Then, the moving average calculation unit 15 transmits the calculated moving average Pave to the correction value setting unit 16 and the target value calculation unit 17.

  Subsequently, the correction value setting unit 16 sets the correction value M according to the amplitude of the power generation amount Pg detected in step S01 and the power storage amount Cb detected in step S02 (step S04, correction value setting). Step). Details of step S04 will be described later. Then, the target value calculation unit 17 calculates the output target value Pt by correcting the moving average Pave calculated in step S03 with the correction value M set in step S04 (step S05, target value setting step). . The target value calculation unit 17 calculates the output target value Pt by adding the correction value M to the moving average Pave, for example. Then, the target value calculation unit 17 transmits the calculated output target value Pt to the charge / discharge amount instruction unit 14.

  Subsequently, the charge / discharge amount instruction unit 14 instructs the charge / discharge amount of the power storage device 5 according to the power generation amount Pg detected in step S01 and the output target value Pt calculated in step S05 (step S06). , Charge / discharge amount instruction step). For example, the charge / discharge amount instruction unit 14 calculates the charge / discharge amount by subtracting the power generation amount Pg from the output target value Pt. Then, the charge / discharge amount instruction unit 14 transmits a charge / discharge command including the calculated charge / discharge amount to the bidirectional converter 6. In this way, a series of processes of the charge / discharge control method is completed.

  Next, the correction value setting process of FIG. 5 will be described in detail with reference to FIG. FIG. 6 is a flowchart showing the correction value setting process.

  First, the bias calculation unit 18 determines whether or not the amplitude of the power generation amount Pg is greater than or equal to the threshold amplitude Ath (step S11). When it is determined in step S11 that the amplitude of the power generation amount Pg is less than the threshold amplitude Ath (step S11; NO), the bias calculation unit 18 determines whether or not the frequency of the power generation amount Pg is equal to or higher than the threshold frequency Fth. Determination is made (step S12). When it is determined in step S12 that the frequency of the power generation amount Pg is less than the threshold frequency Fth (step S12; NO), the bias calculation unit 18 generates the amplitude of the power generation amount Pg (that is, power generation with respect to the moving average Pave in each period). The bias value α is calculated according to the relative displacement (maximum and minimum values of the amount Pg), and the bias value is set to the bias value α. In addition, the bias coefficient determination unit 19 sets the bias coefficient γ by a function system of the charged amount Cb having hysteresis (step S13).

  On the other hand, when it is determined in step S11 that the amplitude of the power generation amount Pg is greater than or equal to the threshold amplitude Ath (step S11; YES), or in step S12, it is determined that the frequency of the power generation amount Pg is greater than or equal to the threshold frequency Fth. When the determination is made (step S12; YES), the bias calculation unit 18 determines that the SOC of the power storage device 5 is greater than 50 + x% and the SOC of the power storage device 5 is less than 50−x% based on the storage amount Cb. It is determined whether or not any of the above is satisfied (step S14). That is, bias calculation unit 18 determines whether or not the absolute value of the difference between the SOC of power storage device 5 and 50% is greater than x%. In step S14, when it is determined that the SOC of power storage device 5 is 50−x% or more and 50 + x% or less (step S14; NO), bias calculation unit 18 sets the bias value to zero (step S15). ).

  On the other hand, when it is determined in step S14 that the SOC of the power storage device 5 is greater than 50 + x% or the SOC of the power storage device 5 is less than 50−x% (step S14; YES), the bias calculating unit 18 Set the value to the bias value β. Then, bias coefficient determination unit 19 sets bias coefficient γ so that the SOC of power storage device 5 approaches 50% (step S16).

  Subsequently, the correction value calculation unit 20 calculates the correction value M according to the bias value and the bias coefficient γ set in step S13, step S15, or step S16 (step S17). The correction value calculation unit 20 calculates, for example, a positive bias value or a negative bias value obtained by multiplying the bias value and the bias coefficient γ as the correction value M. The correction value calculation unit 20 transmits the calculated correction value M to the target value calculation unit 17. In this way, the correction value setting process is completed.

Next, the charging / discharging operation | movement of the electrical storage apparatus 5 in the electric power generation system 1 is demonstrated using the example shown by FIG. When the charged amount Cb (SOC) of the power storage device 5 is 50% and the bias coefficient γ is +1, the output target value Pt becomes the discharge side output target value Pt _{d obtained} by adding the bias value α to the moving average Pave, and the power storage device 5 It tends to discharge. For this reason, the charged amount Cb of the power storage device 5 decreases. When the charged amount Cb of the power storage device 5 decreases to the second charged amount C2, the bias coefficient γ gradually changes from +1 to -1. Thus, the output target value Pt is gradually decreased from the discharge side output target value Pt _d. During this time, the charged amount Cb of the power storage device 5 further decreases from the second charged amount C2, and approaches the end-of-discharge state.

Thereafter, the bias coefficient γ becomes −1, and the output target value Pt becomes the charging side output target value Pt _c obtained by subtracting the bias value α from the moving average Pave, so that the power storage device 5 tends to be charged. For this reason, the power storage amount Cb of the power storage device 5 increases. When the charged amount Cb of the power storage device 5 increases to the first charged amount C1, the bias coefficient γ gradually changes from −1 to +1. As a result, the output target value Pt gradually increases from the charge side output target value Pt _c . During this time, the charged amount Cb of the power storage device 5 further increases from the first charged amount C1 and approaches the end-of-charge state. Thereafter, the bias coefficient γ becomes +1, and the output target value Pt becomes the discharge-side output target value Pt _d obtained by adding the bias value α to the moving average Pave. Therefore, the power storage device 5 tends to discharge again. Such a series of cycles is repeated. Since the power generation amount Pg varies with the passage of time, the moving average Pave and the bias value α are updated with the passage of time according to changes in the power generation amount Pg.

  In this way, whether the power storage device 5 is charged or discharged is expressed by the sign of the bias coefficient γ. Then, by controlling the bias coefficient γ with a function in which the storage amount Cb is provided with hysteresis, the power generation system 1 while slowly and periodically changing the storage device 5 between the end-of-charge state and the end-of-discharge state. Is smoothed.

  Next, simulation results to which the charge / discharge control method is applied will be described. FIG. 7 is a diagram illustrating simulation results of changes in power generation amount, moving average, and output target value. FIG. 8 is a diagram showing a simulation result of the transition of the SOC. The horizontal axis in FIG. 7 indicates time, and the vertical axis indicates power. The horizontal axis in FIG. 8 indicates time, and the vertical axis indicates SOC [%].

  The simulation of FIG. 7 was performed by generating a power generation amount that fluctuates with the passage of time by random numbers and calculating the moving average, the charge side output target value, and the discharge side output target value using the power generation amount. The simulation of FIG. 8 was performed by calculating the transition of the SOC of the power storage device using each of the moving average, the charge side output target value, and the discharge side output target value shown in FIG. 7 as the output target values. The SOC of the power storage device has a starting value at time 0 of 50%.

  As shown in FIG. 8, when the output target value is the charging side output target value, it is understood that the SOC of the power storage device is controlled to the charging side while the output of the power generation system is smoothed. Further, when the output target value is the discharge side output target value, it can be seen that the SOC of the power storage device is controlled to the discharge side while smoothing the output of the power generation system. Thus, according to the charge / discharge control method of the charge / discharge control device, by setting the output target value as the charge side output target value, the power storage device can be brought close to the end-of-charge state, and the output target value is output to the discharge side output. By setting the target value, it can be said that the power storage device can be brought close to the end-of-discharge state.

As described above in detail, in the charge / discharge control device 10 and the charge / discharge control method, in a state where the storage amount Cb is increasing (that is, when the storage device 5 is charged), the charge / discharge control device 10 is more than half the storage capacity of the storage device 5. Until the charged amount Cb reaches the large first charged amount C1, the output target value Pt is set as the charge-side output target value Pt _c that increases the charged amount Cb. For this reason, even if the storage amount Cb exceeds half of the storage capacity, the storage device 5 continues to be charged, and the storage device 5 approaches the end-of-charge state. Thereby, the dispersion | variation in the electrical storage amount of each cell of the electrical storage apparatus 5 is reduced, and the efficient use of the electrical storage apparatus 5 is attained. In a state where the storage amount Cb is increasing, in after the charged amount Cb has reached the first storage amount C1, the output target value Pt is set to the discharge side output target value Pt _d to reduce the storage amount Cb . For this reason, when the charged amount Cb reaches the first charged amount C1, the power storage device 5 is discharged, and the power storage device 5 is suppressed from being charged beyond the end-of-charge state. As a result, the output Ps of the power generation system 1 can be continuously smoothed. As a result, it is possible to reduce the variation in the storage amount of each cell of the power storage device 5 while smoothing the output Ps of the power generation system 1. Then, by periodically putting the power storage device 5 into the end-of-charge state, balanced charging between cells of the power storage device 5 is automatically performed.

In addition, after balance charging between cells of the power storage device 5, if the power storage amount Cb is left for a long time in a state close to the end-of-charge state, the power storage device 5 deteriorates. Therefore, in the charge / discharge control device 10 and the charge / discharge control method, the second power storage that is smaller than half of the power storage capacity of the power storage device 5 in a state where the power storage amount Cb is reduced (that is, when the power storage device 5 is discharged). until the amount C2 storage amount Cb is reached, the output target value Pt is set to the discharge side output target value Pt _d. For this reason, even if the charged amount Cb becomes smaller than half of the charged capacity, the power storage device 5 continues to be discharged, and the power storage device 5 approaches the end-of-discharge state. Further, in a state where the storage amount Cb is decreasing, after the storage amount Cb reaches the second storage amount C2, the output target value Pt is set to the charge side output target value Pt _c . For this reason, when the charged amount Cb reaches the second charged amount C2, the power storage device 5 is charged, and the power storage device 5 is suppressed from being further discharged from the end-of-discharge state. As a result, the output Ps of the power generation system 1 can be continuously smoothed.

Discharge-side output target value Pt _d, so obtained by adding a positive bias value defined in accordance with the amplitude of the power generation amount Pg in the moving average Pave of power generation Pg, output target discharge side output target value Pt _d By setting the value Pt, the possibility that the power generation amount Pg falls below the output target value Pt can be increased. As a result, the charged amount Cb of the power storage device 5 can be reliably reduced, that is, the power storage device 5 can be discharged. The charging-side output target value Pt _c, so obtained by adding a negative bias value defined in accordance with the amplitude of the power generation amount Pg in the moving average Pave of power generation amount Pg, the charging-side output target value Pt _c By setting the output target value Pt, the possibility that the power generation amount Pg exceeds the output target value Pt can be increased. As a result, the storage amount Cb of the power storage device 5 can be reliably increased, that is, the power storage device 5 can be charged.

  Further, when the bias coefficient γ is changed from −1 to +1, the bias coefficient γ is gradually increased from −1 so that it becomes +1 at a predetermined transition time, and the bias coefficient γ is changed from +1 to −1. In this case, it may be set to −1 at a predetermined transition time by gradually decreasing from +1. In this case, the correction value M can be changed gradually, and the sudden change of the output target value Pt can be avoided. For this reason, it is possible to avoid a sudden change in the output Ps of the power generation system 1 and to stabilize the system.

  A bias value α is calculated according to the amplitude of the power generation amount Pg, and a bias coefficient γ is calculated according to the power storage amount Cb of the power storage device 5. Then, the correction value M is calculated by multiplying the bias value α and the bias coefficient γ. Therefore, the influence on the correction value M due to the change in the amplitude of the power generation amount Pg and the influence on the correction value M due to the change in the power storage amount Cb of the power storage device 5 can be separated. It is possible to simplify the calculation of the value M.

  The amplitude and period of the power generation amount Pg change with time. It can be said that the fluctuation of the power generation amount Pg is a state in which the fluctuation of the amount of solar radiation such as cloudy weather is unstable. For example, when the amplitude of the power generation amount Pg is equal to or greater than the threshold amplitude Ath, or when the frequency component of the power generation amount Pg includes a component equal to or higher than the threshold frequency Fth, the power generation amount Pg of the renewable energy power generation device 3 is unstable. Can be considered a state. In such an unstable state, the power storage device 5 is frequently charged and discharged for smoothing the output Ps of the power generation system 1. In such a case, by using the bias value β smaller than the bias value α and the bias coefficient γ, the power storage amount Cb of the power storage device 5 is close to half the power storage capacity of the power storage device 5, It can suppress that the charge / discharge amount of the electrical storage apparatus 5 exceeds the upper limit of the performance of the electrical storage apparatus 5. FIG. Thereby, it can avoid that the electrical storage apparatus 5 will be in a charging / discharging end state, and can suppress that the smoothing process of the output Ps of the electric power generation system 1 stops. As a result, even when the fluctuation period of the power generation amount Pg is short and when the fluctuation amplitude of the power generation amount Pg is large, the output Ps of the power generation system 1 can be smoothed continuously and stably.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment. For example, in the above embodiment, the target value setting unit 13 sets the output target value Pt using the moving average Pave and the correction value M, but the present invention is not limited to this. For example, the target value setting unit 13 may directly change the output target value Pt using a function system of the charged amount Cb having hysteresis as shown in FIG.

  In the above embodiment, the correction value setting unit 16 calculates the correction value M by multiplying the bias value and the bias coefficient γ, but the present invention is not limited to this. For example, the correction value setting unit 16 may change the correction value M using a function system of the charged amount Cb having hysteresis as shown in FIG.

  Further, the bias calculation unit 18 determines whether or not the amplitude of the power generation amount Pg is equal to or greater than a predetermined threshold amplitude Ath, and whether or not the frequency of the power generation amount Pg is equal to or higher than a predetermined threshold frequency Fth. The bias value may be set to the bias value α without determination. In this case, the bias coefficient determination unit 19 may set the bias coefficient γ by a function system of the charged amount Cb having hysteresis.

  When the renewable energy power generation device 3 is a solar power generator, the power generation amount Pg becomes zero at night. For this reason, balance charging can be performed at night without performing output fluctuation smoothing processing. At that time, the power storage amount Cb of the power storage device 5 may be controlled to become the power storage capacity of the power storage device 5 toward the evening. That is, the bias value may be determined by the bias calculation unit 18 and the bias coefficient may be determined by the bias coefficient determination unit 19 so that the charged amount Cb is maximized in the evening in the day. In this case, it is not necessary to purchase electric power necessary only for balance charging, and economical operation is possible.

DESCRIPTION OF SYMBOLS 1 Power generation system 3 Renewable energy power generation device 5 Power storage device 10 Charge / discharge control device 11 Power generation amount detection unit 12 Power storage amount detection unit 13 Target value setting unit 14 Charge / discharge amount instruction unit 15 Moving average calculation unit 16 Correction value setting unit 17 Target Value calculation unit 18 Bias calculation unit 19 Bias coefficient determination unit 20 Correction value calculation unit

Claims (8)

In a power generation system comprising a renewable energy power generation device and a power storage device composed of a plurality of cells, a charge / discharge control device for controlling charge / discharge of the power storage device,
A power generation amount detection unit for detecting a power generation amount of the renewable energy power generation device;
A power storage amount detection unit for detecting a power storage amount of the power storage device;
A target value setting unit that sets an output target value of the power generation system according to the power generation amount detected by the power generation amount detection unit and the power storage amount detected by the power storage amount detection unit;
A charge / discharge amount instruction unit for instructing a charge / discharge amount of the power storage device according to the power generation amount detected by the power generation amount detection unit and the output target value set by the target value setting unit;
With
The target value setting unit, when the storage amount detected by the storage amount detection unit is increasing, until the storage amount reaches a first storage amount that is larger than half of the storage capacity of the storage device. The output target value is set to a charge-side output target value that increases the amount of power storage, and after the amount of power storage reaches the first power storage amount, the output is set to a discharge-side output target value that decreases the power storage amount. A charge / discharge control device for setting a target value.   The target value setting unit, when the storage amount detected by the storage amount detection unit is decreasing, until the storage amount reaches a second storage amount that is smaller than half of the storage capacity of the storage device 2. The output target value is set as the discharge-side output target value, and the output target value is set as the charge-side output target value after the storage amount reaches the second storage amount. Charge-discharge control apparatus as described in. The target value setting unit
A moving average calculation unit that calculates a moving average of the power generation amount detected by the power generation amount detection unit;
A correction value setting unit that sets a correction value according to the amplitude of the power generation amount detected by the power generation amount detection unit and the power storage amount detected by the power storage amount detection unit;
A target value calculation unit for calculating the output target value by correcting the moving average calculated by the moving average calculation unit with the correction value set by the correction value setting unit;
With
The correction value setting unit sets, as the correction value, a positive bias value determined according to the amplitude of the power generation amount or a negative bias value determined according to the amplitude of the power generation amount,
The target value calculation unit calculates the output target value by adding the correction value set by the correction value setting unit to the moving average calculated by the moving average calculation unit. 2. The charge / discharge control device according to 2.   When the correction value is changed from the negative bias value to the positive bias value, the correction value setting unit gradually increases the negative bias value to increase the positive value at a predetermined time. When the correction value is changed to be a bias value, and the correction value is changed from the positive bias value to the negative bias value, the positive bias value is gradually decreased to be predetermined. The charge / discharge control apparatus according to claim 3, wherein the correction value is changed so that the negative bias value is reached in a predetermined time. The correction value setting unit
A bias calculation unit that calculates a bias value according to the amplitude of the power generation amount detected by the power generation amount detection unit;
A bias coefficient determination unit that determines a bias coefficient according to the stored power amount detected by the stored power amount detection unit;
A correction value calculation unit that calculates the correction value by multiplying the bias value calculated by the bias calculation unit and the bias coefficient determined by the bias coefficient determination unit. Item 5. The charge / discharge control device according to Item 4. The target value setting unit is configured such that when the amplitude of the power generation amount detected by the power generation amount detection unit is equal to or larger than a predetermined amplitude, the power storage amount approaches half of the power storage capacity of the power storage device. Set the output target value,
The charging / discharging control apparatus as described in any one of Claims 1-5. When the frequency of the power generation amount detected by the power generation amount detection unit is equal to or higher than a predetermined frequency, the target value setting unit is configured so that the power storage amount approaches half of the power storage capacity of the power storage device. Set the output target value,
The charge / discharge control apparatus as described in any one of Claims 1-6. In a power generation system comprising a renewable energy power generation device and a power storage device composed of a plurality of cells, a charge / discharge control method performed by a charge / discharge control device that controls charge / discharge of the power storage device,
A power generation amount detecting step for detecting a power generation amount of the renewable energy power generation device; and
A storage amount detection step for detecting a storage amount of the power storage device;
A target value setting step of setting an output target value of the power generation system according to the power generation amount detected in the power generation amount detection step and the power storage amount detected in the power storage amount detection step;
A charge / discharge amount instruction step for instructing a charge / discharge amount of the power storage device according to the power generation amount detected in the power generation amount detection step and the output target value set in the target value setting step;
With
In the target value setting step, when the storage amount detected in the storage amount detection step is increasing, until the storage amount reaches a first storage amount that is larger than half of the storage capacity of the storage device. The output target value is set to a charge-side output target value that increases the amount of power storage, and after the amount of power storage reaches the first power storage amount, the output is set to a discharge-side output target value that decreases the power storage amount. A charge / discharge control method for setting a target value.

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