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

Abstract

To smoothly switch between charging and discharging and optimize charged and discharged power in accordance with a balance between generated power and load power consumption in a power storage system that uses generated power.SOLUTION: A power storage system controller 100 executes a charging and discharging mode in which some of a plurality of power storage strings S1 to Sx are placed in a discharge state, and the remaining power storage strings S1 to Sx are placed in a charging standby state, or some of the plurality of power storage strings S1 to Sx are placed in a charging state and the remaining power storage strings S1 to Sx are placed in a discharging standby state. The power storage system controller 100 determines a ratio between the power storage strings S1 to Sx that are placed in the discharging state and the power storage strings S1 to Sx that are placed in the charging standby state, or a ratio between the power storage strings S1 to Sx that are placed in the charging state and the power storage strings S1 to Sx that are placed in the discharge standby state, on the basis of transition prediction information that predicts transitions of generated power of a photovoltaic power generation device 5 and power consumption of a load 4 connected to a power reception point.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Known energy storage systems that utilize solar power generation include a plurality of storage batteries, each of which charges and discharges 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. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-44733 Summary of the Invention [Problem to be solved by the invention]

[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. [Means for solving the problem]

[0006] The battery control device of the present invention is a battery control device for controlling charging and discharging of a power storage system including a power 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 respectively connected to the power converters, and a power generation device connected to the power receiving point, 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 charge 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 discharge standby state, and determines the ratio of the storage batteries in the discharging state to the storage batteries in the charge standby state, or the ratio of the storage batteries in the charging state to the storage batteries in the discharge 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 power receiving point, or the transition between the discharge power and the charge power of the power storage system. and determining a ratio of the storage batteries to be in the discharging state and the storage batteries to be in the charge standby state, or a ratio of the storage batteries to be in the charging state and the storage batteries to be in the discharge standby state, based on a ratio of the predicted discharge power and the predicted charge power of the power storage system included in the transition prediction information. .

[0007] The power storage system of the present invention is 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, 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 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 discharging state and the storage batteries other than these some are in a charging standby state, or in which some of the plurality of storage batteries are in a charging state and the storage batteries other than these some 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 power receiving point, or the transition between the discharged power and the charged power of the power storage system. and determining a ratio of the storage batteries to be in the discharging state and the storage batteries to be in the charge standby state, or a ratio of the storage batteries to be in the charging state and the storage batteries to be in the discharge standby state, based on a ratio of the predicted discharge power and the predicted charge power of the power storage system included in the transition prediction information. .

[0008] A storage battery control method of the present invention is a storage battery control method for a power system including a storage battery system including a plurality of bidirectional power converters connected in parallel to a power receiving point of a power grid and a plurality of storage batteries respectively connected to the power converters, and a power generation device connected to the power receiving point, and is executed using a storage battery control device that controls charging and discharging of the storage battery system, and the method executes a charge / discharge mode in which some of the plurality of storage batteries are in a discharging state and the storage batteries other than the some are in a charging standby state, or in which some of the plurality of storage batteries are in a charging state and the storage batteries other than the some 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 power receiving point, or the transition between the discharged power and the charged power of the storage battery system. and determining a ratio of the storage batteries to be in the discharging state and the storage batteries to be in the charge standby state, or a ratio of the storage batteries to be in the charging state and the storage batteries to be in the discharge standby state, based on a ratio of the predicted discharge power and the predicted charge power of the power storage system included in the transition prediction information. . [Effects of the Invention]

[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. [Brief explanation of the drawings]

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

[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 W1 to 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 facility 3 and the load 4, and supplies power from the power receiving facility 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 facility 3, and supplies power from the photovoltaic power generation device 5 to the power receiving facility 3. The string bus 2 also connects the plurality of power storage strings S1 to Sx to the power receiving facility 3, and supplies power from the plurality of power storage strings S1 to Sx to the power receiving facility 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 regenerated second-hand 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 solar 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 power storage strings S1 to Sx, and converts DC input from the power 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-power storage system 10 of this embodiment is of an AC link type. Note that the type of the PV-power storage system 10 may be a DC link type.

[0018] Each wattmeter W1~W X The power meter W measures the input and 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 solar power generation device 5 and transmits the measured power to the power storage system controller 100.

[0019] The power storage system controller 100 includes power meters W1 to W X ,W GRI ,W PVThe 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. Furthermore, the power storage system controller 100 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-power 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 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 (i.e., power to be sold) of the power receiving facility 3. Also, the output power of the solar power generation device 5 (hereinafter referred to as solar power generation power) P PV indicates a positive value. Furthermore, the input power of load 4 (hereinafter referred to as 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).

number

[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).

number

number

[0023] Figure 3 shows the solar power generation power P PV and load power consumption P Z 4 shows the relationship between the solar power generation power P PV and load power consumption P Z FIG.

[0024] As shown in Figure 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 to t3), and then gradually decreases to the minimum value (from time t2 to t3 to time t4 and after). That is, on a sunny day, the solar power generation power P PV On the other hand, the load power consumption P Z does 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 solar power generation power P PV is the load power consumption P Z (from time t1 to t2 to time t3 to t4), and then the photovoltaic power generation power P PV is the load power consumption P Z The time when the temperature remains below this level continues (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 Therefore, the 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 and the load power consumption P Z If this is not possible, the purchased power P GRI is the load power consumption PZ 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 becomes surplus, so 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 P PV exceeds the charging capacity of the power storage system 1, the surplus solar power generation power P PV A portion of the electricity sold (-P GRI ), or the output of the solar power generation device 5 is restricted.

[0027] Here, the discharge mode is PV is the load power consumption P Z The charging mode is 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 large enough for the solar power generation power P PV and load power consumption P Z There is not enough difference between 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 storage strings S1 to Sx are in a discharging state (hereinafter referred to as a discharging state), and the remaining storage strings S1 to Sx are in a standby state ready to be charged (hereinafter referred to as a charge standby state). When charging in the charge / discharge mode, some of the multiple storage strings S1 to Sx are in a charging state (hereinafter referred to as a charging state), and the remaining storage strings S1 to Sx are in a standby state ready to be discharged (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 it is 0, the power storage system power P BATis 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 it is 0, 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 charge.

[0028] As shown in Figure 4, on days with moving 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 PV is unstable due to the influence of drifting clouds. Therefore, on days with drifting clouds, the solar power generation power P PV is the load power consumption P Z After the period (from time 0 to time t1) during which the photovoltaic power PV and load power consumption P Z The time period from time t1 to time t5 continues, during which the reversal of the magnitude relationship between the photovoltaic power P PV is the load power consumption P Z The time period (from time t5 onwards) during which the voltage remains below this level 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 solar power generation power P PV and load power consumption P ZThe time period (from time t1 to time t5) during which the magnitude relationship between 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 according to 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 discharging mode is being executed in the PV-storage system 10. As shown in this diagram, when the discharging 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 P PV and storage system power P BAT and 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 solar power generation power P PV is the load power consumption P Z When the surplus solar power generation 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 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 not sufficient, the solar power generation power P PV A part of the power sold from the solar power generation device 5 to the power receiving equipment 3 (-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 t4 (time t4 in Fig. 4), the power purchased from the grid P GRI is supplied to 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 Zand, depending on the comparison result, determine the ratio between the sum of the charge power limit values ​​of the storage strings S1 to Sx in the charge mode and the sum of the discharge power limit values ​​of the storage strings S1 to Sx in the discharge mode. The 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 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 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-electricity storage system 10. As shown in this diagram, during discharge in the charge / discharge mode, 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 supplies the power storage system power P BAT In addition, solar power generation power P PV and storage system power P BAT and the load power consumption P Z If this is not possible, purchase 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 BATFurthermore, 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 discharging 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 (information on the current status, weather forecasts, etc.) from a higher-level system (not shown). The power storage system controller 100 refers to the information received from the higher-level system and calculates the amount of solar power generation P from the present time onwards based on, for example, changes in the last hour, conditions in the same time period in the past, weather, etc. PV and load power consumption P Z The 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 ZThe discharge / charge standby ratio is determined based on the comparison result. For example, the discharge / charge standby ratio is determined based on the predicted solar power generation 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 is equal to the average value of, the discharge / charge standby ratio is determined to be 1:1. 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. The average value may be replaced with the maximum value.

[0041] In addition, the discharge / charge standby ratio is, for example, PV is the predicted load power consumption P Z The difference between the two when 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 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 ) is equal to the average value of the discharge / charge standby ratio, the ratio is 1:1. PV is the predicted load power consumption P Z The difference between the two when Z -P PV ) is the average of the predicted solar power generation P PV is the predicted load power consumption P Z The difference between the two when it exceeds PV -PZ ) 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 discharging 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 these 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 discharging 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 discharging state or a charge standby state so that, 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 is as close as possible to the ratio of discharge / charge standby.

[0043] Here, when discharging in 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 BAT is decreased from a positive value to 0, and the storage system power P BAT is decreased from 0 to a negative value. Note that, when discharging 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 a charge standby state.

[0044] 8 is a diagram showing the flow of power during charging when the charge / discharge mode is being executed in the PV-electricity storage system 10. As shown in this diagram, during charging when the charge / 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 1. When the charge capacity of the power storage system 1 is not sufficient, the solar power generation power P PV A part of the power sold from the solar power generation device 5 to the power receiving equipment 3 (-P GRI ) During charging in the charge / discharge mode, some of the power storage strings S1 to Sx in the power storage system 1 are in a charging state, and the remaining power storage strings S1 to Sx are in a discharge standby state.

[0045] The power storage system controller 100 is configured to measure the power consumption of the power meter W when charging in the charge / discharge mode. 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 adjusts the solar power generation power P PV and load power consumption P Z The 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 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 ZThe power storage system controller 100 predicts the transition of the solar power generation power P during the execution of the charge / discharge mode, which is included in the transition prediction information. 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 is equal to the average value of, 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 relative to the average value of is, the higher the proportion of the power storage strings S1 to Sx in the charging state is determined to be. Note that the average value may be replaced with the maximum value.

[0048] The charge / discharge standby ratio is also determined by, for example, the predicted solar power generation 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 Z -P PV 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 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 Z -P PV ) is equal to the average value of the predicted solar power generation PPV is the predicted load power consumption P Z The difference between the two when it exceeds PV -P Z ) is the average of the predicted solar power generation P PV is the predicted load power consumption P Z The difference between the two when Z -P PV ) is larger relative to the average value, the charge / discharge standby ratio is determined so that the proportion of the power storage strings S1 to Sx in the charging state increases. 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 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 BAT is increased from a negative value to 0, and the power storage system power P BAT is increased from 0 to a positive value. Note that, when charging is performed 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 the 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 sales (-P GRI ) and Wattmeter W PV The photovoltaic power P measured by PV and power meters W1 to W X The total value of the charge / discharge power of each storage string S1 to Sx measured by BAT ) and obtain the load power consumption P Z (Step S3). 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 generation power P PV and load power consumption PZ 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 solar power generation power P predicted by 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 power storage system controller 100 determines the charging mode. PV and load power consumption P Z If the difference between the values ​​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 charge / discharge ratio) of the power storage strings S1 to Sx in the charging state or charge standby state to the power storage strings S1 to Sx in the discharge standby state or discharge state according to the execution mode determined in step S4. Furthermore, when the power storage system controller 100 determines the execution mode to be the charge / discharge mode in step S4, it 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 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 based on the magnitude relationship between the predicted solar power generation 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 calculates the predicted solar power generation power P PV and load power consumption P Z The charge / discharge ratio n:m is determined based on the magnitude relationship between the predicted solar power generation 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 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 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 charge / discharge 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. Furthermore, the execution condition is met 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 meters W1 to W X The total power measured by the storage system power P BAT is a positive value, the power storage system controller 100 determines that the power storage system 1 is discharging. BAT If the value of the power storage system 1 is negative, it is determined that the power storage system 1 is currently charging.

[0064] The power storage system controller 100 is configured to GRIBased on this, 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 the power storage system controller 100 is buying or selling power, and the power storage system controller 100 determines whether the power storage system controller 100 is buying or selling power P 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 is set to P to eliminate the influence of noise. GRI = 0 is set to a value slightly shifted in the positive direction. Similarly, the threshold value for determining whether or not power is being sold (hereinafter referred to as the power selling threshold value) P 0c is set to P 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. Also, 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 GRI and the reference value P refc and 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 refd If it is determined that the purchased power P GRI and the reference value P refd and 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 Figure 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 standard value P refcand 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 standard 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 it is smaller, it is determined whether or not there is a surplus in the charging capacity of the power storage system 1 (step S9). If it is determined in step S9 that there is a surplus in the charging capacity of the power storage system 1, the process proceeds to step 11, and if it is determined in step S9 that there is no surplus in the charging capacity of the power storage system 1, the process proceeds to step 10.

[0071] When there is no remaining charge capacity in 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 BAT is 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 is configured to 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 the amount of charge).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 controls the purchased power P GRI is the reference value P refd If it is greater than the above, it is determined whether or not there is a surplus in the discharge capacity of the power storage system 1 (step S14). If it is determined in step S14 that there is a surplus in the discharge capacity of the power storage system 1, the process proceeds to step 16, and if it is determined in step S14 that there is no surplus in the discharge capacity of the power storage system 1, the process proceeds to step 17.

[0076] If there is no surplus power in the discharge capacity of the power storage system 1, the power storage system controller 100 purchases power as an emergency measure (step S17). On the other hand, if there is surplus power in the discharge capacity of the power storage system 1, the power storage system controller 100 purchases power as an emergency measure (step S17). 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 BATis 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 and the buying / selling state of the power storage system 1 are stable, so that processes such as steps S19 and S20 described below are not required.

[0080] If 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 suppresses charging of the electricity storage system 1 by purchasing electricity. 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 power discharged from the power 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. As described above, the charge / discharge ratio is the ratio 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. As a result, the photovoltaic power generation power P 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 solar power generation power P PV is the load power consumption P Z The difference between the two when 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 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 excess or shortage of the solar power generation power P PV By covering the shortage with the discharge of the power storage system 1, the amount of purchased electricity can be reduced, and the solar power generation power P PV By storing the surplus electricity in the electricity storage system 1 through charging, it is possible to reduce the amount of electricity 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 ) and the charge / discharge ratio is determined according to the 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 power supply voltage Vcc exceeds 1 / 2V, 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 in a discharging state and the sum of the charge power limit values ​​of the power storage strings S1 to Sx 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 in a charging state and the sum of the discharge power limit values ​​of the power storage strings S1 to Sx 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 GRI ) is the absolute value of the power purchase threshold P 0d The absolute value of the reference value P is larger than 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 greater than or equal to the GRI ) is the absolute value of the power selling threshold P 0c The absolute value of the reference value P is greater than refc The charging power (-P BAT ) is adjusted. This adjusts the power sold (-P 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 the power storage strings S1 to Sx are in a discharged state and a charge mode in which all the power storage strings S1 to Sx are in a charged state. However, it is not essential to execute the discharge mode and the charge mode, and the charge / discharge mode may be executed at all times.

[0091] In the above embodiment, the power storage system controller 100 calculates 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 power storage system 1, 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 discharging power storage strings S1 to Sx decreases. Therefore, the discharging power storage strings S1 to Sx may be swapped with the charge-standby power storage strings S1 to Sx 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 power storage strings S1 to Sx in the charged state decreases. Therefore, the power storage strings S1 to Sx in the charged state may be swapped with the power storage strings S1 to Sx in the discharge standby state around the time when the charge capacity of the power storage strings S1 to Sx becomes zero. In this case, the charge / discharge ratio may be updated according to the most recent operating state.

[0094] Furthermore, 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. Furthermore, 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 one 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 power storage system controller 100 executes the processes of steps S1 to S4 and S6 to S20 shown in Figs. 9, 11, and 12, with the aim of reducing the amount of power purchased and sold. [Explanation of symbols]

[0096] 1: Energy storage system 4: Load 5: Solar power generation equipment (power generation equipment) 10: PV-storage system (power system) 100: Storage system controller (storage battery control device) PCS1 to PCSx: Power converters 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 (load power consumption) S1 to Sx: Storage strings (storage batteries)

Claims

1. A power system including a power storage system including a plurality of bidirectional power converters connected in parallel to a power receiving point of a power grid, a plurality of storage batteries respectively connected to the power converters, and a power generation device connected to the power receiving point, comprising: a storage battery control device that controls charging and discharging of the storage system; a charge / discharge mode is executed in which some of the plurality of storage batteries are in a discharging state and the remaining storage batteries are in a charge 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 discharge standby state; determining a ratio of the storage batteries to be placed in the discharging state and the storage batteries to be placed in the charge standby state, or a ratio of the storage batteries to be placed in the charging state and the storage batteries to be placed in the discharge standby state, based on transition prediction information that predicts a transition between the power generated by the power generation device and the power consumed by the load connected to the power receiving point, or a transition between the discharge power and the charge power of the power storage system; A battery control device that 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 discharge 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.

2. 2. The battery control device according to claim 1, wherein a determination is made as to whether each of the plurality of storage batteries is to be placed in the discharging state or the charging standby state in accordance with a ratio between the sum of the discharge power limit values ​​of the storage batteries to be placed in the discharging state and the sum of the charge power limit values ​​of the storage batteries to be placed in the charging standby state, or a determination is made as to whether each of the plurality of storage batteries is to be placed in the charging state or the discharge standby state in accordance with a ratio between the sum of the charge power limit values ​​of the storage batteries to be placed in the charging state and the sum of the discharge power limit values ​​of the storage batteries to be placed in the discharge standby state.

3. 2. The battery control device according to claim 1, wherein, when the storage system is discharging, if the absolute value of the power purchased from the power grid is equal to or greater than a first threshold, the battery control device adjusts the discharged power of the storage system so that the absolute value of the power purchased approaches a first reference value whose absolute value is greater than the first threshold.

4. 4. The battery control device according to claim 1, wherein when the storage system is being charged, if the absolute value of the power sold to the power grid is equal to or greater than a second threshold, the battery control device adjusts the charging power of the storage system so that the absolute value of the power sold approaches a second reference value whose absolute value is greater than the second threshold.

5. A power storage system provided in a power system in which a power generation device is connected to a power receiving point of the power grid, a plurality of bidirectional power converters connected in parallel to the power receiving point; a plurality of storage batteries respectively connected to the power converter; a battery control device that controls charging and discharging of the plurality of batteries; Equipped with The battery control device includes: a charge / discharge mode is executed in which some of the plurality of storage batteries are in a discharging state and the remaining storage batteries are in a charge 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 discharge standby state; determining a ratio of the storage batteries to be placed in the discharging state and the storage batteries to be placed in the charge standby state, or a ratio of the storage batteries to be placed in the charging state and the storage batteries to be placed in the discharge standby state, based on transition prediction information that predicts a transition between the power generated by the power generation device and the power consumed by the load connected to the power receiving point, or a transition between the discharge power and the charge power of the power storage system; The ratio of the storage batteries to be placed in the discharging state and the storage batteries to be placed in the charging standby state, or the ratio of the storage batteries to be placed in the charging state and the storage system to be placed in the discharge standby state, is determined based on the ratio between the predicted discharge power and the predicted charge power of the storage system included in the transition prediction information.

6. A battery control method for a power system including a power storage system including a plurality of bidirectional power converters connected in parallel to a power receiving point of a power grid and a plurality of storage batteries respectively connected to the power converters, and a power generation device connected to the power receiving point, the method being executed using a battery control device that controls charging and discharging of the power storage system, a charge / discharge mode is executed in which some of the plurality of storage batteries are in a discharging state and the remaining storage batteries are in a charge 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 discharge standby state; determining a ratio of the storage batteries to be placed in the discharging state and the storage batteries to be placed in the charge standby state, or a ratio of the storage batteries to be placed in the charging state and the storage batteries to be placed in the discharge standby state, based on transition prediction information that predicts a transition between the power generated by the power generation device and the power consumed by the load connected to the power receiving point, or a transition between the discharge power and the charge power of the power storage system; A battery control method for determining 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 discharge 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.

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