Storage battery control device, electricity storage system, and storage battery control method

Abstract

An electricity storage system controller (100) executes a charge / discharge mode in which a part of a plurality of electricity storage strings (S1 to Sx) is set to a discharge state and the electricity storage strings (S1 to Sx) other than the part thereof are set to a charge standby state, or a part of the plurality of electricity storage strings (S1 to Sx) is set to a charge state and the electricity storage strings (S1 to Sx) other than the part thereof are set to a discharge standby state. On the basis of transition prediction information obtained by predicting the transitions of the generated power of a solar power generation device (5) and the power consumption of a load (4) connected to a power reception point, the ratio between the electricity storage strings (S1 to Sx) set to the discharge state and the electricity storage strings (S1 to Sx) set to the charge standby state or the ratio between the electricity storage strings (S1 to Sx) set to the charge state and the electricity storage strings (S1 to Sx) set to the discharge standby state is determined.

Description

Battery control device, power storage system, and battery control method

[0001] The present invention relates to a storage battery control device, a power storage system, and a storage battery control method.

[0002] A known energy storage system that uses solar power generation includes multiple storage batteries, each of which is charged and discharged independently by switching a switch on and off (see, for example, Patent Document 1). In the energy storage system described in Patent Document 1, when charging of one of the storage batteries is stopped by turning off the corresponding switch, the other storage batteries are in a state of discharging or are able to discharge to a load.

[0003] Japanese Patent Application Publication No. 2012-44733

[0004] The power storage system described in Patent Document 1 does not take into consideration the ratio of storage batteries to be charged to storage batteries to be discharged or prepared for discharge. Therefore, depending on the balance between solar power generation power and load power consumption, there may be an excess or deficiency in charge / discharge power.

[0005] In view of the above circumstances, the present invention aims to provide a battery control device, a battery storage system, and a battery control method that enable smooth switching between charging and discharging in a battery storage system that uses generated power, and that enable optimization of charging and discharging power according to the balance between generated power and load power consumption.

[0006] The battery control device of the present invention is a battery control device that controls the charging and discharging of a power storage system in a power system that includes a plurality of bidirectional power converters connected in parallel to a receiving point of a power grid and a plurality of storage batteries each connected to the power converters, and a power generation device connected to the receiving point, and executes a charge / discharge mode in which some of the plurality of storage batteries are in a discharging state and the other storage batteries are in a charging standby state, or in which some of the plurality of storage batteries are in a charging state and the other storage batteries are in a discharging standby state, and determines the ratio of the storage batteries to be in the discharging state and the charging standby state, or the ratio of the storage batteries to be in the charging state and the charging standby state, based on transition prediction information that predicts the transition between the generated power of the power generation device and the power consumption of a load connected to the receiving point, or the transition between the discharged power and the charged power of the power storage system.

[0007] The energy storage system of the present invention is an energy storage system provided in an electric power system in which a power generation device is connected to a power receiving point of an electric power grid, and includes a plurality of bidirectional power converters connected in parallel to the power receiving point, a plurality of storage batteries respectively connected to the power converters, and a storage battery control device that controls the charging and discharging of the plurality of storage batteries, and the storage battery control device executes a charge / discharge mode in which some of the plurality of storage batteries are in a discharged state and the storage batteries other than those some are in a charge standby state, or in which some of the plurality of storage batteries are in a charged state and the storage batteries other than those some are in a discharge standby state, and determines the ratio of the storage batteries to be in the discharged state and the storage batteries to be in the charge standby state, or the ratio of the storage batteries to be in the charged state and the storage batteries to be in the discharge standby state, based on transition prediction information that predicts the transition between the generated power of the power generation device and the power consumption of a load connected to the power receiving point, or the transition between the discharged power and the charged power of the energy storage system.

[0008] The battery control method of the present invention is a battery control method implemented in a power system including a storage system having a plurality of bidirectional power converters connected in parallel to a receiving point of a power grid and a plurality of storage batteries each connected to the power converters, and a power generation device connected to the receiving point, using a storage battery control device that controls the charging and discharging of the storage system, and executes a charge / discharge mode in which some of the plurality of storage batteries are in a discharging state and the remaining storage batteries are in a charging standby state, or in which some of the plurality of storage batteries are in a charging state and the remaining storage batteries are in a discharging standby state, and determines the ratio of the storage batteries in the discharging state to the storage batteries in the charging standby state, or the ratio of the storage batteries in the charging state to the storage batteries in the discharging standby state, based on transition prediction information that predicts the transition between the power generated by the power generation device and the power consumption of a load connected to the receiving point, or the transition between the discharged power and the charged power of the storage system.

[0009] According to the present invention, in an electricity storage system that uses generated power, it is possible to smoothly switch between charging and discharging, and to optimize the charging and discharging power according to the balance between the generated power and the load power consumption.

[0010] FIG. 1 is a diagram showing an outline of a power storage system and a PV-storage system including a power storage system controller according to an embodiment of the present invention. FIG. 2 is a diagram for explaining the definition of positive and negative power under a power receiving point of a PV-storage system. FIG. 3 is a diagram showing the relationship between photovoltaic power generation power and load power consumption for each time period on a sunny day. FIG. 4 is a diagram showing the relationship between photovoltaic power generation power and load power consumption for each time period on a day with moving clouds. FIG. 5 is a diagram showing the flow of power when a discharging mode is being executed in a PV-storage system. FIG. 6 is a diagram showing the flow of power when a charging mode is being executed in a PV-storage system. FIG. 7 is a diagram showing the flow of power when discharging in a charge / discharge mode in a PV-storage system. FIG. 8 is a diagram showing the flow of power when charging in a charge / discharge mode in a PV-storage system. FIG. 9 is a flowchart showing the processing of the power storage system controller. FIG. 10 is a diagram for explaining a threshold value used by the power storage system controller to determine whether power is being purchased or sold, and a reference value used by the power storage system controller to control the power purchased and the power sold. FIG. 11 is a flowchart showing the processing of the power storage system controller. FIG. 12 is a flowchart showing the processing of the power storage system controller.

[0011] The present invention will be described below in accordance with preferred embodiments. Note that the present invention is not limited to the embodiments described below, and the embodiments can be modified as appropriate without departing from the spirit of the present invention. In addition, in the embodiments described below, some components are omitted from illustration and description, but for the details of the omitted technologies, publicly known or well-known technologies are applied as appropriate within the scope of not causing any contradictions with the content described below.

[0012] 1 is a diagram showing an outline of a power storage system 1 and a PV (Photovoltaic) power storage system 10, each including a power storage system controller 100 according to an embodiment of the present invention. As shown in this diagram, the power storage system 1 includes x (x is an integer of 2 or more) power storage strings S1 to Sx, x power converters PCS1 to PCSx, and x power meters W. １ ~W ＸThe power storage system includes x string controllers C1 to Cx, and a power storage system controller 100. Each power converter PCS1 to PCSx is provided corresponding to each power storage string S1 to Sx, and each power storage string S1 to Sx is connected to a string bus 2 via each power converter PCS1 to PCSx. Furthermore, the multiple power storage strings S1 to Sx are connected in parallel to the string bus 2.

[0013] The string bus 2 connects the power receiving equipment 3 and the load 4, and supplies power from the power receiving equipment 3 to the load 4. The string bus 2 also connects the photovoltaic power generation device 5 and the load 4 via a power converter 6, and supplies power from the photovoltaic power generation device 5 to the load 4. The string bus 2 also connects a plurality of power storage strings S1 to Sx to the load 4, and supplies power from the plurality of power storage strings S1 to Sx to the load 4. The string bus 2 also connects the photovoltaic power generation device 5 and the plurality of power storage strings S1 to Sx, and supplies power from the photovoltaic power generation device 5 to the plurality of power storage strings S1 to Sx. The string bus 2 also connects the photovoltaic power generation device 5 and the power receiving equipment 3, and supplies power from the photovoltaic power generation device 5 to the power receiving equipment 3. The string bus 2 also connects the plurality of power storage strings S1 to Sx to the power receiving equipment 3, and supplies power from the plurality of power storage strings S1 to Sx to the power receiving equipment 3.

[0014] Each of the power storage strings S1 to Sx is a stationary power source including a plurality of storage battery modules M connected in series. Although not particularly limited, the power storage strings S1 to Sx in this embodiment are refurbished secondhand storage batteries, and the degree of deterioration of each storage battery module M varies. The storage battery modules M are, for example, secondary batteries such as lithium ion batteries and lithium ion capacitors. The storage battery modules M are charged by receiving power from the power receiving equipment 3 and the photovoltaic power generation device 5 via the string bus 2. On the other hand, the storage battery modules M discharge power to the load 4 and the power receiving equipment 3 via the string bus 2.

[0015] The power storage strings S1 to Sx may include a plurality of storage battery cells or storage battery packs connected in series, instead of a plurality of storage battery modules M connected in series.

[0016] Each power converter PCS1 to PCSx is a bidirectional AC / DC converter that converts AC input from the string bus 2 into DC and outputs it to the storage strings S1 to Sx, and converts DC input from the storage strings S1 to Sx into AC and outputs it to the string bus 2.

[0017] A power converter 6 is provided between the solar power generation device 5 and the string bus 2. The power converter 6 is a DC / AC converter, and converts the direct current output from the solar power generation device 5 into alternating current and outputs it to the string bus 2. That is, the PV-energy storage system 10 of this embodiment is of an AC link type. Note that the type of the PV-energy storage system 10 may be a DC link type.

[0018] Each wattmeter W １ ~W Ｘ measures the input / output power of each of the power storage strings S1 to Sx and transmits the measured power to the power storage system controller 100. ＧＲＩ A power meter W is provided. ＧＲＩ measures the input / output power of the power receiving equipment 3 and transmits the measured power to the power storage system controller 100. ＰＶ measures the output power of the photovoltaic power generation device 5 and transmits the measured power to the power storage system controller 100 .

[0019] The power storage system controller 100 is １ ~W Ｘ , W ＧＲＩ , W ＰＶ The power storage system controller 100 executes a discharge mode, a charge mode, and a charge / discharge mode, which will be described later, based on the power measured by the power storage system controller 100 and transition prediction information that predicts transitions in the photovoltaic power generation power and the load power consumption. The power storage system controller 100 also transmits instruction values, such as a charge / discharge power instruction value and a charge / discharge current instruction value, that determine the charge / discharge amount of each of the power storage strings S1 to Sx to the string controllers C1 to Cx. Each of the string controllers C1 to Cx controls the power converters PCS1 to PCSx in accordance with the instruction values.

[0020] 2 is a diagram for explaining the definition of positive and negative power in the vicinity of the power receiving point of the PV-electricity storage system 10. As shown in this figure, the direction of current flowing in the vicinity of the power receiving point is defined as the positive direction. Therefore, the output power of the power storage system 1 (hereinafter referred to as the power storage system power) P ＢＡＴ indicates a positive value, and the storage system power P ＢＡＴ is the input power of each of the power storage strings S1 to Sx. In addition, the output power of the power receiving equipment 3 (hereinafter referred to as purchased power) P ＧＲＩ indicates a positive value, and the purchased power P indicates a negative value. ＧＲＩ is the input power of the power receiving facility 3 (i.e., the power to be sold). In addition, the output power of the solar power generation device 5 (hereinafter, the solar power generation power) P ＰＶ indicates a positive value. Furthermore, the input power of the load 4 (hereinafter referred to as the load power consumption) P Ｚ indicates a negative value.

[0021] The relationship of power under the power receiving point is expressed by the following equation (1).

[0022] Therefore, the storage system power P ＢＡＴ is expressed by the following equation (2), and the load power consumption P Ｚ is expressed by the following equation (3).

[0023] FIG. 3 shows the solar power generation power P for each time period on a sunny day. ＰＶ and load power consumption P Ｚ 4 is a graph showing the relationship between the photovoltaic power generation power P ＰＶ and load power consumption P Ｚ FIG.

[0024] As shown in FIG. 3, on a sunny day, the solar power generation power P ＰＶ gradually increases from the minimum value to the maximum value (from time 0 to time t2-t3), and then gradually decreases to the minimum value (from time t2-t3 to time t4 and thereafter). That is, on a sunny day, the photovoltaic power generation power P ＰＶ On the other hand, the load power consumption P Ｚdoes not fluctuate significantly on a daily basis, but fluctuates slightly on an hourly basis. Therefore, on sunny days, the solar power generation power P ＰＶ is the load power consumption P Ｚ After a period of time (from time 0 to time t1 to t2) during which the photovoltaic power generation power P ＰＶ is the load power consumption P Ｚ (from time t1-t2 to time t3-t4), and then the photovoltaic power generation power P ＰＶ is the load power consumption P Ｚ (from time t3 to t4 until time t4 onwards).

[0025] Solar power generation power P ＰＶ is the load power consumption P Ｚ During the time period when the solar power generation power P ＰＶ Then, the load power consumption P Ｚ Since it is not possible to cover the power storage system power P ＢＡＴ The load power consumption P Ｚ In the discharge mode, the solar power generation power P ＰＶ and storage system power P ＢＡＴ The load power consumption P Ｚ If this is not possible, the purchased power P ＧＲＩ is the load power consumption P Ｚ It is used for.

[0026] Solar power generation power P ＰＶ is the load power consumption P Ｚ During the time period when the solar power generation power P ＰＶ Since there is a surplus, the surplus solar power generation power P ＰＶ The charging power of the storage system 1 (-P ＢＡＴ In the charging mode, the surplus solar power generation power P ＰＶ exceeds the charging capacity of the power storage system 1, the surplus solar power generation power P ＰＶ A part of the electricity sold (-P ＧＲＩ ), or the output of the solar power generation device 5 is suppressed.

[0027] Here, the discharge mode is the solar power generation power P ＰＶ is the load power consumption P ＺThe charging mode is a mode executed in a time period that is sufficiently small relative to the solar power generation power P ＰＶ is the load power consumption P Ｚ This mode is executed in a time period that is sufficiently large for the photovoltaic power P ＰＶ and load power consumption P Ｚ There is not enough difference between the two, and the solar power generation power P ＰＶ and load power consumption P Ｚ The charge / discharge mode is executed in a time period when the magnitude relationship between the power storage strings S1 to Sx and the power storage strings S1 to Sx may be reversed. When discharging in the charge / discharge mode, some of the multiple power storage strings S1 to Sx are in a discharging state (hereinafter referred to as a discharging state), and the remaining power storage strings S1 to Sx are in a standby state in preparation for charging (hereinafter referred to as a charge standby state). When charging in the charge / discharge mode, some of the multiple power storage strings S1 to Sx are in a charging state (hereinafter referred to as a charging state), and the remaining power storage strings S1 to Sx are in a standby state in preparation for discharging (hereinafter referred to as a discharge standby state). Here, the charge standby state is a state in which the power storage system power P ＢＡＴ is not limited to a state where the power storage system power P ＢＡＴ is a positive value (discharge state). That is, the power storage strings S1 to Sx in the charge standby state are set to a bypass state that is optimal for charging (capable of charging more power), but when the power storage system 1 is requested to discharge, it may discharge to the extent possible. Also, the discharge standby state is a state in which the power storage system power P ＢＡＴ is not limited to a state where the power storage system power P ＢＡＴ is a negative value (charging state). That is, the power storage strings S1 to Sx in the discharge standby state are set to a bypass state that is optimal for discharging (capable of discharging a larger amount of power), but may be charged to the extent possible when the power storage system 1 is requested to be charged.

[0028] As shown in FIG. 4, on days with drifting clouds, the solar power generation power P ＰＶ rises from the minimum value to the maximum value on a daily basis (from time 0 to time t3), and then falls to the minimum value (from time t3 to time t5 and thereafter). However, the photovoltaic power generation power P ＰＶThe solar power generation power P is unstable due to the influence of drifting clouds. ＰＶ is the load power consumption P Ｚ After the time (from time 0 to time t1) during which the photovoltaic power generation power P ＰＶ and load power consumption P Ｚ The time period from time t1 to time t5 during which the magnitude relationship between the photovoltaic power generation output P ＰＶ is the load power consumption P Ｚ The time period (from time t5 onwards) during which the voltage Vcc is below 0 continues.

[0029] On days with drifting clouds, the solar power generation power P ＰＶ is the load power consumption P Ｚ Therefore, on days with drifting clouds, the time period during which the discharge mode is executed is longer than on sunny days. Also, on days with drifting clouds, the time period during which the photovoltaic power generation power P ＰＶ and load power consumption P Ｚ The time period (from time t1 to time t5) during which the magnitude relationship between the voltage Vcc and the charge / discharge mode is repeatedly reversed continues for a long time. Therefore, on days with drifting clouds, the time period during which the charge / discharge mode is executed is longer than on sunny days.

[0030] The power storage system controller 100 detects the solar power generation power P ＰＶ and load power consumption P Ｚ The power storage system controller 100 determines the mode from among the discharge mode, the charge mode, and the charge / discharge mode depending on the magnitude relationship between the photovoltaic power P ＰＶ is the load power consumption P Ｚ If the difference between the two is predicted to be equal to or greater than a predetermined value, the power storage system controller 100 determines the discharge mode. ＰＶ is the load power consumption P Ｚ If the difference between the two is predicted to be equal to or greater than a predetermined value, the power storage system controller 100 determines the charging mode. ＰＶ and load power consumption P Ｚ If the difference between the two is predicted to be less than a predetermined value, the charge / discharge mode is selected.

[0031] Solar power generation power P ＰＶ and load power consumption P Ｚ The magnitude relationship may be predicted from the current value, or may be predicted from a moving average of the current value and past values, or may be predicted from a weather forecast.

[0032] 5 is a diagram showing the flow of power when the discharge mode is being executed in the PV-storage system 10. As shown in this figure, when the discharge mode is being executed, the photovoltaic power generation power P ＰＶ is supplied from the solar power generation device 5 to the load 4, and the power storage system power P ＢＡＴ is supplied from the power storage system 1 to the load 4. In addition, the photovoltaic power generation power P ＰＶ and storage system power P ＢＡＴ The load power consumption P Ｚ If this is not possible, the purchased power P ＧＲＩ is supplied from the power receiving equipment 3 to the load 4 .

[0033] When the discharge mode is executed, the power storage system controller 100 ＧＲＩ Purchased power P measured by ＧＲＩ The storage system power P ＢＡＴ In addition, when the discharge mode is executed, the power storage system controller 100 adjusts the photovoltaic power generation power P ＰＶ is the load power consumption P Ｚ (time t1 in FIG. 4), the surplus photovoltaic power P ＰＶ The selling power (-P ＧＲＩ ) to the grid, or the output of the photovoltaic power generation device 5 is suppressed.

[0034] 6 is a diagram showing the flow of power when the charging mode is being executed in the PV-storage system 10. As shown in this diagram, when the charging mode is being executed, the photovoltaic power generation power P ＰＶ is supplied from the solar power generation device 5 to the load 4 and the power storage system 1. When the charge capacity of the power storage system 1 is insufficient, the solar power generation power P ＰＶ A part of the sold power (-P ＧＲＩ ) is supplied.

[0035] When the charging mode is executed, the power storage system controller 100 ＧＲＩ The power sold (-P ＧＲＩ ) is as small as possible, the storage system power (-P ＢＡＴ In addition, when the charging mode is executed, the power storage system controller 100 adjusts the solar power generation power P ＰＶ is the load power consumption P Ｚ When the power consumption falls below the predetermined value (time t4 in FIG. 4), the power purchased from the grid P ＧＲＩ is supplied to the load 4.

[0036] The power storage system controller 100 detects the solar power generation power P ＰＶ and load power consumption P Ｚ The predicted solar power generation power P included in the transition forecast information ＰＶ and load power consumption P Ｚ and, depending on the comparison result, determine the ratio between the sum of the charge power limit values ​​of the power storage strings S1 to Sx in the charge mode and the sum of the discharge power limit values ​​of the power storage strings S1 to Sx in the discharge mode. ＰＶ and the load power consumption P Ｚ In this case, the predicted solar power generation power P ＰＶ Average value of and predicted load power consumption P Ｚ If the average value of the predicted solar power generation power P ＰＶ The average value of the predicted load power consumption P Ｚ The ratio is determined so that the smaller the ratio relative to the average value of the power storage strings S1 to Sx, the higher the proportion of the power storage strings S1 to Sx that are in the discharging state. Note that the average value may be replaced with the maximum value.

[0037] 7 is a diagram showing the flow of power during discharge in the charge / discharge mode in the PV-storage system 10. As shown in this figure, during discharge in the charge / discharge mode, the photovoltaic power P ＰＶ is supplied from the solar power generation device 5 to the load 4, and the power storage system 1 supplies the power storage system power P ＢＡＴ In addition, solar power generation power P ＰＶand storage system power P ＢＡＴ The load power consumption P Ｚ If this is not possible, purchased power (+P ＧＲＩ ) is supplied from the power receiving facility 3 to the load 4. Here, during discharging when the charge / discharge mode is executed, in the power storage system 1, some of the power storage strings S1 to Sx are in a discharging state, and the remaining power storage strings S1 to Sx are in a charge standby state.

[0038] During discharge in the charge / discharge mode, the power storage system controller 100 ＧＲＩ Purchased power P measured by ＧＲＩ The storage system power P ＢＡＴ Furthermore, when transitioning from the discharge mode to the charge / discharge mode, the power storage system controller 100 determines the ratio of the power storage strings S1 to Sx in the discharge state to the power storage strings S1 to Sx in the charge standby state (hereinafter referred to as the discharge / charge standby ratio), and whether each of the power storage strings S1 to Sx is in the discharge state or the charge standby state. At this time, the power storage system controller 100 adjusts the solar power generation power P ＰＶ and load power consumption P Ｚ The ratio of the discharging / standby state and the state (discharging state or charge standby state) of each of the power storage strings S1 to Sx are determined based on transition prediction information that predicts the transition between the power storage strings S1 to Sx and information on the discharge power limit value and the charge power limit value of the power storage strings S1 to Sx. Note that a discharge current limit value may be used instead of the discharge power limit value, and a charge current limit value may be used instead of the charge power limit value.

[0039] The power storage system controller 100 detects the solar power generation power P ＰＶ and load power consumption P Ｚ Information to be referenced when predicting the transition of solar power generation power (past ＰＶ and load power consumption P Ｚ The power storage system controller 100 receives information from the upper system (not shown), such as information on the current status of the solar power generation P from the present time onward, based on, for example, the change in the last hour, the situation in the same time period in the past, the weather, etc. ＰＶ and load power consumption P ＺThe power storage system controller 100 predicts the transition of the solar power generation power P ＰＶ and load power consumption P Ｚ It is not necessary to predict the transition of the solar power generation power P ＰＶ and load power consumption P Ｚ The transition of the power consumption may be predicted and transmitted to the power storage system controller 100.

[0040] The power storage system controller 100 calculates the predicted photovoltaic power generation power P when the charge / discharge mode is executed, which is included in the transition prediction information. ＰＶ and load power consumption P Ｚ The discharge / charge standby ratio is determined based on the comparison result. The discharge / charge standby ratio is determined based on, for example, the predicted photovoltaic power generation power P ＰＶ and the load power consumption P Ｚ In this case, the predicted solar power generation power P ＰＶ Average value of and predicted load power consumption P Ｚ If the average value of the predicted solar power generation power P ＰＶ The average value of the predicted load power consumption P Ｚ The discharge / charge standby ratio is determined so that the proportion of the power storage strings S1 to Sx in the discharging state increases as the value of the discharge / charge standby ratio decreases relative to the average value of the power storage strings S1 to Sx. Note that the average value may be replaced with the maximum value.

[0041] The discharge / charge standby ratio is, for example, ＰＶ is the predicted load power consumption P Ｚ The difference between the two when it is below Ｚ -P ＰＶ ) and the predicted solar power generation power P ＰＶ is the predicted load power consumption P Ｚ The difference between the two when it exceeds ＰＶ -P Ｚ In this case, the predicted solar power generation power P ＰＶ is the predicted load power consumption P Ｚ The difference between the two when it is below Ｚ -P ＰＶ ) and the predicted solar power generation power P ＰＶis the predicted load power consumption P Ｚ The difference between the two when it exceeds ＰＶ -P Ｚ ) is equal to the average value of the predicted solar power generation power P ＰＶ is the predicted load power consumption P Ｚ The difference between the two when it is below Ｚ -P ＰＶ ) is the predicted solar power generation power P ＰＶ is the predicted load power consumption P Ｚ The difference between the two when it exceeds ＰＶ -P Ｚ ) is larger relative to the average value of the power storage strings S1 to Sx, the discharge / charge standby ratio is determined so that the proportion of the power storage strings S1 to Sx in the discharge state becomes higher. Note that the average value may be replaced with the maximum value.

[0042] The string controllers C1 to Cx of each of the power storage strings S1 to Sx calculate a discharge power limit value and a charge power limit value for each of the power storage strings S1 to Sx based on the SOC (State of Charge) and SOH (State of Health) of the storage battery module M, and transmit the calculated values ​​to the power storage system controller 100. The power storage system controller 100 determines whether to put each of the power storage strings S1 to Sx into a discharge state or a charge standby state based on the discharge power limit value and the charge power limit value received from each of the string controllers C1 to Cx. The power storage system controller 100 determines whether to put each of the power storage strings S1 to Sx into a discharge state or a charge standby state, for example, so that the ratio between the sum of the discharge power limit values ​​of the power storage strings S1 to Sx in the discharge state and the sum of the charge power limit values ​​of the power storage strings S1 to Sx in the charge standby state is as close as possible to the discharge / charge standby ratio.

[0043] Here, when discharging in the charge / discharge mode, the load power consumption P Ｚ is the solar power generation power P ＰＶ In this case, the power storage system controller 100 may detect the power storage system power P ＢＡＴis decreased from a positive value to 0, and the power storage system power P ＢＡＴ is decreased from 0 to a negative value. Note that, during discharge in the charge / discharge mode, the power storage system power P ＢＡＴ It is not essential to maintain the power storage system power P of the power storage strings S1 to Sx in the charge standby state during discharge in the charge / discharge mode. ＢＡＴ may be set to a positive value to discharge the power storage strings S1 to Sx in the charge standby state.

[0044] 8 is a diagram showing the flow of power during charging in the charge / discharge mode in the PV-storage system 10. As shown in this figure, during charging in the charge / discharge mode, the photovoltaic power P ＰＶ is supplied from the solar power generation device 5 to the load 4 and the power storage system 1. When the charge capacity of the power storage system 1 is insufficient, the solar power generation power P ＰＶ A part of the sold power (-P ＧＲＩ Here, during charging when the charge / discharge mode is executed, in the power storage system 1, some of the power storage strings S1 to Sx are in a charging state, and the remaining power storage strings S1 to Sx are in a discharge standby state.

[0045] During charging in the charge / discharge mode, the power storage system controller 100 ＧＲＩ The power sold (-P ＧＲＩ ) is as small as possible, the storage system power (-P ＢＡＴ ; charging power). Furthermore, when transitioning from the charging mode to the charge / discharge mode, the power storage system controller 100 determines the ratio of the power storage strings S1 to Sx in the charging state to the power storage strings S1 to Sx in the discharge standby state (hereinafter referred to as the charge / discharge standby ratio), and whether each of the power storage strings S1 to Sx is in the charging state or the discharge standby state. At this time, the power storage system controller 100 determines the ratio of the photovoltaic power generation power P ＰＶ and load power consumption P ＺThe charge / discharge standby ratio and the state of each of the power storage strings S1 to Sx are determined based on transition prediction information that predicts the transition between the power storage strings S1 to Sx and the information on the charge power limit value and the discharge power limit value of the power storage strings S1 to Sx. Note that a charge current limit value may be used instead of the charge power limit value, and a discharge current limit value may be used instead of the discharge power limit value.

[0046] The power storage system controller 100 controls the solar power generation power P ＰＶ and load power consumption P Ｚ The power storage system controller 100 predicts the transition of the solar power generation power P when the charge / discharge mode is executed, by referring to the information received from the higher-level system. ＰＶ and load power consumption P Ｚ The charge / discharge standby ratio is determined according to the comparison result.

[0047] The charge / discharge standby ratio is, for example, ＰＶ and the load power consumption P Ｚ In this case, the predicted solar power generation power P ＰＶ Average value of and predicted load power consumption P Ｚ If the average value of the predicted solar power generation power P is equal to the average value of the predicted solar power generation power P, the charge / discharge standby ratio is determined to be 1:1. ＰＶ The average value of the predicted load power consumption P Ｚ The larger the value of the standby charge / discharge cycle relative to the average value of the power storage strings S1 to Sx, the higher the proportion of the power storage strings S1 to Sx in the charging state. Note that the average value may be replaced with the maximum value.

[0048] The charge / discharge standby ratio is, for example, ＰＶ is the predicted load power consumption P Ｚ The difference between the two when it exceeds ＰＶ -P Ｚ ) and the predicted solar power generation power P ＰＶ is the predicted load power consumption P Ｚ The difference between the two when it is below Ｚ -P ＰＶIn this case, the predicted solar power generation power P ＰＶ is the predicted load power consumption P Ｚ The difference between the two when it exceeds ＰＶ -P Ｚ ) and the predicted solar power generation power P ＰＶ is the predicted load power consumption P Ｚ The difference between the two when it is below Ｚ -P ＰＶ ) is equal to the average value of the predicted solar power generation power P ＰＶ is the predicted load power consumption P Ｚ The difference between the two when it exceeds ＰＶ -P Ｚ ) is the predicted solar power generation power P ＰＶ is the predicted load power consumption P Ｚ The difference between the two when it is below Ｚ -P ＰＶ ) is larger relative to the average value of the power storage strings S1 to Sx, the charge / discharge standby ratio is determined so that the proportion of the power storage strings S1 to Sx in the charging state becomes higher. Note that the average value may be replaced with the maximum value.

[0049] Furthermore, the power storage system controller 100 determines whether to put each of the power storage strings S1 to Sx into a charging state or a discharge standby state based on the charging power limit value and the discharging power limit value of each of the power storage strings S1 to Sx received from each of the string controllers C1 to Cx. The power storage system controller 100 determines whether to put each of the power storage strings S1 to Sx into a charging state or a discharge standby state so that, for example, the ratio between the total value of the charging power limit values ​​of the power storage strings S1 to Sx into a charging state and the total value of the discharging power limit values ​​of the power storage strings S1 to Sx into a discharge standby state is as close as possible to the charging / discharging standby ratio.

[0050] Here, when charging in the charge / discharge mode, the load power consumption P Ｚ is the solar power generation power P ＰＶ In this case, the power storage system controller 100 may control the power storage system power P ＢＡＴis increased from a negative value to 0, and the power storage system power P ＢＡＴ is increased from 0 to a positive value. During charging in the charge / discharge mode, the power storage system power P ＢＡＴ It is not essential to maintain the power storage system power P of the power storage strings S1 to Sx in the discharge standby state during charging in the charge / discharge mode. ＢＡＴ may be set to a negative value to charge the power storage strings S1 to Sx in the discharge standby state.

[0051] 9, 11, and 12 are flowcharts showing the processing of the power storage system controller 100. First, as shown in Fig. 9, when operation of the power storage system 1 is started, the power storage system controller 100 initializes parameters such as a charge power limit value, a discharge power limit value, and the SOC and SOH of the storage battery module M, as well as constants used in calculation processing (step S1). Next, the power storage system controller 100 acquires information on the state of each of the power storage strings S1 to Sx, such as a charge power limit value, a discharge power limit value, and the SOC and SOH of each storage battery module M, from each string controller C1 to Cx (step S2).

[0052] Next, the power storage system controller 100 detects the power meter W ＧＲＩ Purchased power P measured by ＧＲＩ Or power sold (-P ＧＲＩ ) and wattmeter W ＰＶ The solar power generation power P measured by ＰＶ and Wattmeter W １ ~W Ｘ The total value of the charge / discharge power of each of the power storage strings S1 to Sx measured by ＢＡＴ ) and the load power consumption P Ｚ (Step S3). １ ~W Ｘ It is not essential to measure the charge / discharge power of each of the power storage strings S1 to Sx by the above method, and the power storage system power P ＢＡＴ may be calculated.

[0053] Next, the power storage system controller 100 calculates the solar power generation power P ＰＶ and load power consumption P Ｚ The execution mode of the power storage system 1 is determined to be one of the discharge mode, the charge mode, and the charge / discharge mode according to the magnitude relationship between the photovoltaic power generation power P ＰＶ and load power consumption P Ｚ The magnitude relationship between the photovoltaic power P ＰＶ and load power consumption P Ｚ It is also possible to compare with the most recent solar power generation power P ＰＶ The moving average value of and the most recent load power consumption P Ｚ It is also possible to compare with the moving average value of the solar power generation power P ＰＶ and load power consumption P Ｚ The relationship between the solar power generation power P and the weather forecast is ＰＶ and load power consumption P Ｚ It may also be compared with

[0054] In step S4, the power storage system controller 100 calculates the solar power generation power P ＰＶ is the load power consumption P Ｚ The difference between the two (P Ｚ -P ＰＶ ) is equal to or greater than a predetermined value P', the power storage system controller 100 determines the discharging mode. ＰＶ is the load power consumption P Ｚ The difference between the two (P ＰＶ -P Ｚ ) is equal to or greater than a predetermined value P', the charging mode is determined. ＰＶ and load power consumption P Ｚ If the difference is less than a predetermined value P', the charge / discharge mode is selected.

[0055] Next, the power storage system controller 100 determines the ratio (hereinafter referred to as the charge / discharge ratio) of the power storage strings S1 to Sx in the charging state or the charge standby state to the power storage strings S1 to Sx in the discharge standby state or the discharging state in accordance with the execution mode determined in step S4. Furthermore, when the execution mode is determined to be the charge / discharge mode in step S4, the power storage system controller 100 determines the state (discharging state / charge standby state or charging state / discharge standby state) of each of the power storage strings S1 to Sx (step S5).

[0056] In step S5, the energy storage system controller 100 sets the charge / discharge ratio (charge:discharge) in the discharge mode to 0:x, the charge / discharge ratio in the charge mode to x:0, and the charge / discharge ratio in the charge / discharge mode to n:m (n and m are integers, and n+m=x).

[0057] In step S5, the power storage system controller 100 calculates the predicted photovoltaic power generation power P ＰＶ and load power consumption P Ｚ The charge / discharge ratio n:m is determined according to the magnitude relationship between the predicted photovoltaic power P ＰＶ The average value of the predicted load power consumption P Ｚ The charge / discharge ratio n:m is determined so that the proportion (m / (n+m)) of the power storage strings S1 to Sx in the discharging state increases as the value of n:m decreases relative to the average value.

[0058] On the other hand, in step S5, the power storage system controller 100 determines whether the predicted photovoltaic power generation power P ＰＶ and load power consumption P Ｚ The charge / discharge ratio n:m is determined according to the magnitude relationship between the predicted photovoltaic power P ＰＶ The average value of the predicted load power consumption P Ｚ The charge / discharge ratio n:m is determined so that the proportion (n / (n+m)) of the power storage strings S1 to Sx in the charged state increases as the value of n increases relative to the average value of n:m.

[0059] In addition, in step S5, when transitioning from the discharge mode to the charge / discharge mode, the storage system controller 100 determines whether to put each storage string S1 to Sx into a discharge state or a charge / discharge standby state so that the ratio between the sum of the discharge power limit values ​​of the storage strings S1 to Sx in the discharge state and the sum of the charge power limit values ​​of the storage strings S1 to Sx in the charge / discharge standby state is as close as possible to the charge / discharge ratio.

[0060] On the other hand, in step S5, when transitioning from the charging mode to the charging / discharging mode, the storage system controller 100 determines whether to put each of the storage strings S1 to Sx into a charging state or a discharge standby state so that the ratio between the sum of the charging power limit values ​​of the storage strings S1 to Sx in a charging state and the sum of the discharging power limit values ​​of the storage strings S1 to Sx in a discharge standby state is as close as possible to the charging / discharging ratio.

[0061] Next, the power storage system controller 100 controls the power converters PCS1 to PCSx so that the charge / discharge ratio and the state of each of the power storage strings S1 to Sx are updated to the ratio determined in step S5 (step S6).

[0062] Next, the power storage system controller 100 determines which of the first, second, and third operation modes has its execution condition met (step S7). The first operation mode is determined to be the charge mode or the charge / discharge mode in step S4, and the execution condition is met when charging is in progress and power is being sold. The second operation mode is determined to be the discharge mode or the charge / discharge mode in step S4, and the execution condition is met when discharging is in progress and power is being purchased. The third operation mode is determined to be the execution condition when the execution conditions for the first and second operation modes are not met.

[0063] In step S7, the power storage system controller 100 calculates the power storage system power P ＢＡＴ Specifically, the power storage system controller 100 determines whether the power storage system 1 is charging or discharging based on the power meter W １ ~W Ｘ The total power of the power storage system P is the total power measured byＢＡＴ On the other hand, the power storage system controller 100 determines that the power storage system 1 is discharging when the power storage system power P ＢＡＴ is a negative value, it is determined that the power storage system 1 is being charged.

[0064] The power storage system controller 100 determines the purchased power P ＧＲＩ Based on the above, it is determined whether power is being purchased from the grid or sold to the grid. Hereinafter, a method for determining whether power is being purchased or sold will be described with reference to FIG.

[0065] FIG. 10 shows the threshold value when the power storage system controller 100 determines whether power is being purchased or sold, and the power storage system controller 100 determines whether power is being purchased or sold. ＧＲＩ and power sold (-P ＧＲＩ ) and the reference value when controlling the purchased power P ＧＲＩ When is a positive value, power is being purchased, and the purchased power P ＧＲＩ If the value is negative, the power is being sold. Here, the threshold value (hereinafter referred to as the power purchase threshold value) P ０ｄ In order to eliminate the influence of noise, ＧＲＩ Similarly, the threshold value for determining whether or not power is being sold (hereinafter referred to as the power selling threshold value) P ０ｃ In order to eliminate the influence of noise, ＧＲＩ = 0 in the negative direction. When the execution condition of the third operation mode is satisfied, the purchased power P ＧＲＩ is the power selling threshold P ０ｃ Larger power purchase threshold P ０ｄ The reference value P shown in FIG. ｒｅｆｃ , P ｒｅｆｄ More on this later.

[0066] As shown in Fig. 9, if it is determined in step S7 that the execution condition for the first operation mode is met, the process proceeds to step S8 in Fig. 11, and if it is determined in step S7 that the execution condition for the second operation mode is met, the process proceeds to step S13 in Fig. 12. Furthermore, if it is determined in step S7 that the execution condition for the third operation mode is met, the process proceeds to step S18.

[0067] When the execution condition for the first operation mode is met, the power storage system controller 100 ＧＲＩ is the reference value P ｒｅｆｃ Is it smaller than the purchased power P? ＧＲＩ is the reference value P ｒｅｆｃ Is it larger than the purchased power P? ＧＲＩ and the reference value P ｒｅｆｃ In step S8, it is determined whether the purchased power P ＧＲＩ is the reference value P ｒｅｆｃ If it is determined that the purchased power P ＧＲＩ is the reference value P ｒｅｆｃ If it is determined that the purchased power P is greater than the predetermined value, the process proceeds to step S12. ＧＲＩ and the reference value P ｒｅｆｃ is equal to (purchased power P ＧＲＩ and the reference value P ｒｅｆｃ If it is determined that the difference between the two is equal to or less than the threshold value, the process proceeds to step S2 in FIG.

[0068] On the other hand, when the execution condition for the second operation mode is met, the power storage system controller 100 ＧＲＩ is the reference value P ｒｅｆｄ Is it larger than the purchased power P? ＧＲＩ is the reference value P ｒｅｆｄ Is it smaller than the purchased power P? ＧＲＩ and the reference value P ｒｅｆｄ In step S13, it is determined whether the purchased power P ＧＲＩ is the reference value P ｒｅｆｄ If it is determined that the purchased power P ＧＲＩ is the reference value P ｒｅｆｄIf it is determined that the purchased power P ＧＲＩ and the reference value P ｒｅｆｄ is equal to (purchased power P ＧＲＩ and the reference value P ｒｅｆｄ If it is determined that the difference between the two is equal to or less than the threshold value, the process proceeds to step S2 in FIG.

[0069] As shown in FIG. 10, the reference value P ｒｅｆｃ is a negative value, and the power selling threshold P ０ｃ From the viewpoint of suppressing the amount of electricity sold, the reference value P ｒｅｆｃ and the power selling threshold P ０ｃ It is desirable that the difference between the reference value P ｒｅｆｄ is a positive value, and the power purchase threshold P ０ｄ From the viewpoint of reducing the amount of purchased electricity, the reference value P ｒｅｆｄ and the power purchase threshold P ０ｄ It is desirable that the difference between

[0070] As shown in FIG. 11, the power storage system controller 100 ＧＲＩ is the reference value P ｒｅｆｃ If the difference is smaller than the above, it is determined whether or not the charge capacity of the power storage system 1 has a surplus (step S9). If it is determined in step S9 that the charge capacity of the power storage system 1 has a surplus, the process proceeds to step S11. If it is determined in step S9 that the charge capacity of the power storage system 1 does not have a surplus, the process proceeds to step S10.

[0071] When there is no surplus power in the charging capacity of the power storage system 1, the power storage system controller 100 ＰＶ is reduced by one step by a predetermined control amount (step S10: output suppression). ＧＲＩ is the reference value P ｒｅｆｃ In step S10, the power may be sold at market price as an emergency measure.

[0072] On the other hand, when the charging capacity of the power storage system 1 has a surplus, the power storage system controller 100 ＢＡＴis decreased by one step by a predetermined control amount (step S11: increase in charge amount). ＧＲＩ is the reference value P ｒｅｆｃ This will reduce the amount of electricity sold.

[0073] The power storage system controller 100 determines the purchased power P ＧＲＩ is the reference value P ｒｅｆｃ If it is larger, the storage system power P ＢＡＴ is increased by one step by a predetermined control amount (step S12: decrease in charge amount). ＧＲＩ is the reference value P ｒｅｆｃ approaching.

[0074] As shown in FIG. 12, the power storage system controller 100 ＧＲＩ is the reference value P ｒｅｆｄ If it is smaller, the storage system power P ＢＡＴ is reduced by one step by a predetermined control amount (step S15: reduce the discharge amount). ＧＲＩ is the reference value P ｒｅｆｄ approaching.

[0075] On the other hand, the power storage system controller 100 ＧＲＩ is the reference value P ｒｅｆｄ If the difference is greater than the predetermined value, it is determined whether or not the discharge capacity of the power storage system 1 has a surplus (step S14). If it is determined in step S14 that the discharge capacity of the power storage system 1 has a surplus, the process proceeds to step S16. If it is determined in step S14 that the discharge capacity of the power storage system 1 does not have a surplus, the process proceeds to step S17.

[0076] When the power storage system 1 has no surplus power in the discharge capacity, the power storage system controller 100 purchases power as an emergency measure (step S17). On the other hand, when the power storage system 1 has surplus power in the discharge capacity, the power storage system controller 100 purchases power as an emergency measure (step S18). ＢＡＴ is increased by one step by a predetermined control amount (step S16: increase in discharge amount). ＧＲＩ is the reference value P ｒｅｆｄ This will reduce the amount of electricity purchased.

[0077] 9, when the execution condition for the third operation mode is met, the power storage system controller 100 determines whether the first condition, the second condition, or the third condition is met (step S18). ＢＡＴ is less than 0 (charging) and the purchased power P ＧＲＩ is the power purchase threshold P ０ｄ The second condition is that the storage system power P ＢＡＴ is 0 or more (discharging) Purchased power P ＧＲＩ is the power selling threshold P ０ｃ The third condition is that the purchased power P ＧＲＩ is the power selling threshold P ０ｃ Larger power purchase threshold P ０ｄ The condition is that it is smaller than.

[0078] If it is determined in step S18 that the first condition is met, the process proceeds to step S19, and if it is determined in step S18 that the second condition is met, the process proceeds to step S20. Here, if the first condition or the second condition is met in step S18, an irregular state has occurred in the charging and discharging of the power storage system 1 and the buying and selling of power. Therefore, in steps S19 and S20 described below, the power storage system controller 100 executes processing to stabilize the charging and discharging state of the power storage system 1 and the buying and selling state of power.

[0079] On the other hand, if it is determined in step S18 that the third condition is met, the process proceeds to step S2. In this case, the charging / discharging state of the power storage system 1 and the buying / selling state of the power are stable, so that the processes in steps S19 and S20 described below are not necessary.

[0080] When it is determined in step S18 that the first condition is met, the power storage system controller 100 ＢＡＴ is increased by one step by a predetermined control amount (step S19: decrease the charge amount). This reduces the charging of the power storage system 1 by purchasing power. The process proceeds from step S19 to step S2.

[0081] If it is determined in step S18 that the second condition is met, the power storage system controller 100 ＢＡＴ is decreased by one stage by a predetermined control amount (step S20: decrease in discharge amount), thereby suppressing the sale of electricity discharged from the electricity storage system 1. The process proceeds from step S20 to step S2.

[0082] As described above, the power storage system controller 100 of this embodiment executes a charge / discharge mode in which some of the power storage strings S1 to Sx are in a discharging state and the other power storage strings S1 to Sx are in a charge standby state, or in which some of the power storage strings S1 to Sx are in a charging state and the other power storage strings S1 to Sx are in a discharge standby state. This allows smooth switching between charging and discharging of the power storage system 1.

[0083] Here, the power storage system controller 100 calculates the solar power generation power P ＰＶ and load power consumption P Ｚ The charge / discharge ratio is determined based on transition prediction information that predicts the transition between the power storage strings S1 to Sx in the discharging state and the power storage strings S1 to Sx in the charge standby state, or the ratio between the power storage strings S1 to Sx in the charging state and the power storage strings S1 to Sx in the discharge standby state. ＰＶ and load power consumption P Ｚ The discharge power (+P ＢＡＴ ) and charging power (-P ＢＡＴ For example, during the time period when the charge / discharge mode is executed, the photovoltaic power generation power P ＰＶ is the load power consumption P Ｚ The difference between the two when it is below Ｚ -P ＰＶ ) is the solar power generation power P ＰＶ is the load power consumption P Ｚ The difference between the two when it exceeds ＰＶ -P Ｚ), the proportion of the power storage strings S1 to Sx in the discharging state or the discharge standby state can be increased. ＰＶ is the load power consumption P Ｚ The difference between the two when it exceeds ＰＶ -P Ｚ ) is the solar power generation power P ＰＶ is the load power consumption P Ｚ The difference between the two when it is below Ｚ -P ＰＶ ), the proportion of the power storage strings S1 to Sx in the charging state or the charging standby state can be increased. ＢＡＴ ) and charging power (-P ＢＡＴ Therefore, it is possible to prevent the occurrence of excess or deficiency in the photovoltaic power generation power P ＰＶ The shortage of the solar power generation power P can be covered by discharging the power storage system 1, thereby reducing the amount of purchased power. ＰＶ The surplus power can be stored by charging the power storage system 1, thereby reducing the amount of power sold.

[0084] The power storage system controller 100 also calculates the solar power generation power P ＰＶ and load power consumption P Ｚ The discharge power (+P ＢＡＴ ) and charging power (-P ＢＡＴ ) is used to determine the charge / discharge ratio. ＢＡＴ ) is the predicted charging power (-P ＢＡＴ ), the larger the difference between the two when the charging power (-P ＢＡＴ ) is the discharge power (+P ＢＡＴ ), the greater the difference between the two when the voltages exceed 10 V and 10 V, the higher the proportion of the power storage strings S1 to Sx in the charging state or the charging standby state can be.

[0085] Furthermore, the power storage system controller 100 determines whether to put each of the power storage strings S1 to Sx into a discharging state or a charge standby state in accordance with the ratio between the sum of the discharge power limit values ​​of the power storage strings S1 to Sx to be in a discharging state and the sum of the charge power limit values ​​of the power storage strings S1 to Sx to be in a charge standby state. Alternatively, the power storage system controller 100 determines whether to put each of the power storage strings S1 to Sx into a charging state or a discharge standby state in accordance with the ratio between the sum of the charge power limit values ​​of the power storage strings S1 to Sx to be in a charging state and the sum of the discharge power limit values ​​of the power storage strings S1 to Sx to be in a discharge standby state.

[0086] This allows, for example, the ratio between the sum of the discharge power limit values ​​of the power storage strings S1 to Sx in the discharging state and the sum of the charge power limit values ​​of the power storage strings S1 to Sx in the charge standby state to approach the charge / discharge ratio. Also, the ratio between the sum of the charge power limit values ​​of the power storage strings S1 to Sx in the charging state and the sum of the discharge power limit values ​​of the power storage strings S1 to Sx in the discharge standby state to approach the charge / discharge ratio. Therefore, it is possible to optimize the charge / discharge ratio according to the charge / discharge power limit values.

[0087] Furthermore, when the power storage system 1 is discharging, the power storage system controller 100 purchases power (+P ＧＲＩ ) is the power purchase threshold P ０ｄ If the power purchase amount is more than or equal to the above, the power purchase amount (+P ＧＲＩ ) is the absolute value of the power purchase threshold P ０ｄ The reference value P ｒｅｆｄ The discharge power (+P ＢＡＴ ) is adjusted. This adjusts the purchased power (+P ＧＲＩ ) as the reference value P ｒｅｆｄ can be stabilized to a value close to

[0088] Furthermore, when the power storage system 1 is being charged, the power storage system controller 100 controls the power sold to the power grid (-P ＧＲＩ ) is the power selling threshold P ０ｃ If the power sold is equal to or greater than the ＧＲＩ ) is the absolute value of the power selling threshold P ０ｃ The reference value Pｒｅｆｃ The charging power (-P ＢＡＴ ) is adjusted. ＧＲＩ ) as the reference value P ｒｅｆｃ can be stabilized to a value close to

[0089] The present invention has been described above based on the above embodiment, but the present invention is not limited to the above embodiment, and modifications may be made within the scope of the spirit of the present invention, and publicly known or well-known technologies may be combined as appropriate.

[0090] For example, in the above embodiment, the power storage system controller 100 executes a discharge mode in which all of the power storage strings S1 to Sx are in a discharged state and a charge mode in which all of the power storage strings S1 to Sx are in a charged state. However, execution of the discharge mode and the charge mode is not essential, and the charge / discharge mode may be executed at all times.

[0091] In the above embodiment, the power storage system controller 100 controls the solar power generation power P ＰＶ and load power consumption P Ｚ Based on the transition prediction information that predicts the transition of the required discharge power (+P ＢＡＴ ) and charging power (-P ＢＡＴ ) was predicted. Then, the power storage system controller 100 calculated the predicted discharge power (+P ＢＡＴ ) and charging power (-P ＢＡＴ However, the power storage system controller 100 determines the charge / discharge ratio based on the discharge power (+P ＢＡＴ ) and charging power (-P ＢＡＴ ) may be acquired from a higher-level system or the like, and the charge / discharge ratio may be determined based on the acquired transition prediction information.

[0092] In the above embodiment, as the discharge progresses during discharging in the charge / discharge mode, the discharge capacity of the power storage strings S1 to Sx in the discharging state decreases. Therefore, the power storage strings S1 to Sx in the discharging state may be swapped with the power storage strings S1 to Sx in the charge standby state before and after the discharge capacity of the power storage strings S1 to Sx is exhausted. In this case, the charge / discharge ratio may be updated according to the most recent operating state.

[0093] In the above embodiment, as charging progresses during charging in the charge / discharge mode, the charge capacity of the charged power storage strings S1 to Sx decreases. Therefore, the charged power storage strings S1 to Sx may be swapped with the discharge-standby power storage strings S1 to Sx around the time when the charge capacity of the power storage strings S1 to Sx is exhausted. In this case, the charge / discharge ratio may be updated according to the most recent operating state.

[0094] In addition, in the above embodiment, charging of the power storage system 1 by purchasing power and selling of power by discharging the power storage system 1 are not performed, but these may be performed as necessary. In addition, in the above embodiment, each of the multiple storage batteries connected in parallel to the power receiving point is a storage string S1 to Sx, but it is not essential that each storage battery is configured as a storage string S1 to Sx, and each storage battery may be configured as a single storage battery. Furthermore, in the above embodiment, the power generation device is a solar power generation device 5, but the power generation device may be any device whose generated power varies depending on the environment, such as a wind power generation device or a tidal power generation device.

[0095] <Reference Example> In this reference example, the charge / discharge ratio is constant when the charge / discharge mode is executed, and the charge / discharge ratio is not determined by the power storage system controller 100. On the other hand, in this reference example, the object is to reduce the amount of power purchased and sold, and the power storage system controller 100 executes the processes of steps S1 to S4 and S6 to S20 shown in Figs. 9, 11, and 12.

[0096] Although various embodiments have been described above, it goes without saying that the present invention is not limited to such examples. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present invention. Furthermore, the components of the above embodiments may be combined in any manner as long as they do not deviate from the spirit of the invention.

[0097] This application is based on a Japanese patent application (Patent Application No. 2023-105014) filed on June 27, 2023, the contents of which are incorporated herein by reference.

[0098] 1: Energy storage system 4: Load 5: Photovoltaic power generation device (power generation device) 10: PV-energy storage system (power system) 100: Energy storage system controller (battery control device) PCS1 to PCSx: Power converter P ０ｃ　 : power selling threshold (second threshold) P ０ｄ　 : Power purchase threshold (first threshold) P ＢＡＴ : Power storage system power (discharge power, charge power) P ＧＲＩ : Purchased electricity (sold electricity) P ＰＶ　 : Solar power generation (power generation) P ｒｅｆｃ　　　 : Reference value (second reference value) P ｒｅｆｄ　　　 : Reference value (first reference value) P Ｚ　　 : Load power consumption (power consumption of load) S1 to Sx: Power storage string (storage battery)

Claims

1. A battery control device for controlling charging and discharging of the battery storage system in a power system including a plurality of bidirectional power converters connected in parallel to a receiving point of a power grid and a plurality of storage batteries each connected to the power converters, and a power generation device connected to the receiving point, the battery control device executing a charge / discharge mode in which some of the plurality of storage batteries are in a discharged state and the other storage batteries are in a charge standby state, or in which some of the plurality of storage batteries are in a charged state and the other storage batteries are in a discharge standby state, and determining the ratio of the storage batteries in the discharged state and the charge standby state, or the ratio of the storage batteries in the charged state and the charge standby state, based on transition prediction information that predicts the transition between the generated power of the power generation device and the power consumption of a load connected to the receiving point, or the transition between the discharged power and the charge power of the battery storage system.

2. A battery control device as described in claim 1, which determines the ratio of the storage batteries to be in the discharging state and the storage batteries to be in the charging standby state, or the ratio of the storage batteries to be in the charging state and the storage batteries to be in the discharging standby state, based on the ratio between the predicted discharge power and the predicted charge power of the storage system included in the transition prediction information.

3. A battery control device as described in claim 2, which determines whether each of multiple storage batteries will be in the discharging state or the charging standby state depending on the ratio between the sum of the discharge power limit values ​​of the storage batteries to be in the discharging state and the sum of the charge power limit values ​​of the storage batteries to be in the charging standby state, or determines whether each of multiple storage batteries will be in the charging state or the discharging standby state depending on the ratio between the sum of the charge power limit values ​​of the storage batteries to be in the charging state and the sum of the discharge power limit values ​​of the storage batteries to be in the discharging standby state.

4. A battery control device as described in claim 1, which adjusts the discharged power of the energy storage system so that, when the absolute value of the power purchased from the power grid is equal to or greater than a first threshold value during discharging of the energy storage system, the absolute value of the power purchased approaches a first reference value having an absolute value greater than the first threshold value.

5. A battery control device as described in claim 1 or 4, which adjusts the charging power of the storage system so that, when the absolute value of the power to be sold to the power grid is equal to or greater than a second threshold value during charging of the storage system, the absolute value of the power to be sold approaches a second reference value having an absolute value greater than the second threshold value.

6. A power storage system provided in a power system in which a power generation device is connected to a power receiving point of a power grid, comprising: a plurality of bidirectional power converters connected in parallel to the power receiving point; a plurality of storage batteries respectively connected to the power converters; and a storage battery control device that controls charging and discharging of the plurality of storage batteries, wherein the storage battery control device executes a charge / discharge mode in which some of the plurality of storage batteries are in a discharged state and the storage batteries other than said some are in a charge standby state, or in which some of the plurality of storage batteries are in a charged state and the storage batteries other than said some are in a discharge standby state, and determines the ratio of the storage batteries in the discharged state and the storage batteries in the charge standby state, or the ratio of the storage batteries in the charged state and the storage batteries in the discharge standby state, based on transition prediction information that predicts the transition between the generated power of the power generation device and the power consumption of a load connected to the power receiving point, or the transition between the discharged power and the charged power of the storage system.

7. A battery control method for a power system including a battery storage system having a plurality of bidirectional power converters connected in parallel to a power receiving point of a power grid and a plurality of storage batteries each connected to the power converters, and a power generation device connected to the power receiving point, said battery control method being executed using a battery control device that controls charging and discharging of the battery storage system, wherein a charge / discharge mode is executed in which some of the plurality of storage batteries are in a discharged state and the other storage batteries are in a charge standby state, or a charge / discharge mode is executed in which some of the plurality of storage batteries are in a charged state and the other storage batteries are in a discharge standby state, and the battery control method determines the ratio of the storage batteries in the discharged state and the charge standby state, or the ratio of the storage batteries in the charged state and the charge standby state, based on transition prediction information that predicts the transition between the generated power of the power generation device and the power consumption of a load connected to the power receiving point, or the transition between the discharged power and the charged power of the battery storage system.

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