Power storage system and control method thereof

Abstract

To provide a power storage system that can perform appropriate control without cooperation with a power converter of a photovoltaic power generation device, and a method for controlling the same.SOLUTION: The present disclosure is a power storage system that is provided between a load and a power converter providing independent output according to photovoltaic power generation, and comprises: an AC electric path that reaches an output terminal with which the load is connected from an input terminal for receiving the independent output; a power conversion unit that is between the AC electric path and a storage battery and performs bi-directional power conversion between DC and AC; and a control unit that controls the power conversion unit. The control unit receives setting of a lead-in current value as a prediction value received from the power converter, and controls the power conversion unit so that a current value obtained by subtracting a load current value supplied to the load from the lead-in current value becomes the value of a current fed from the AC electric path to the power conversion unit.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a power storage system and a control method thereof.

Background Art

[0002] The number of small-scale electricity consumers such as ordinary households installing solar power generation devices is increasing. Such a solar power generation device can be connected to the commercial power grid through a power conversion device and sell electricity. Also, during a power outage, the power conversion device disconnected from the commercial power grid can be self-operated, and power can be supplied to specific loads that are desired to be used even during a power outage by self-generated output.

[0003] Furthermore, in recent years, a distributed power system in which a power storage system equipped with a storage battery is installed together with a solar power generation device has begun to spread (see, for example, Patent Document 1). During a power outage, power is supplied to specific loads in the consumer's home by self-generated output, and if there is a surplus of power that can be generated, the storage battery can be charged to effectively utilize the power that can be generated without waste.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] When a distributed power system with a storage battery installed in parallel with a photovoltaic power generation device is newly introduced as a set, it is also possible to connect a photovoltaic panel and a storage battery to a single power conversion device with hybrid functions and perform integrated advanced control. However, when adding a storage system later to a customer who already has a photovoltaic power generation device while effectively using the existing equipment, the photovoltaic power generation device and the storage system will be controlled separately. In this case, from the perspective of the storage system side, it is unclear how much self-sufficient output can be drawn from the photovoltaic power generation device.

[0006] An object of the present disclosure is to provide a storage system and a control method thereof that can perform appropriate control without cooperating with the power conversion device of a photovoltaic power generation device.

Means for Solving the Problems

[0007] The present disclosure includes the following inventions. However, the present invention is defined by the scope of the claims.

[0008] 《Storage System》 The present disclosure is a storage system provided between a power conversion device that provides self-sufficient output by photovoltaic power generation and a load, an AC circuit from an input terminal that receives the self-sufficient output to an output terminal to which the load is connected, a power conversion unit that is between the AC circuit and the storage battery and performs bidirectional power conversion between DC and AC, and a control unit that controls the power conversion unit, wherein the control unit receives a setting of a drawn current value as an expected value received from the power conversion device, and controls the power conversion unit such that a current value obtained by subtracting a load current value supplied to the load from the drawn current value becomes a current value sent from the AC circuit to the power conversion unit. It is a storage system.

[0009] 《Control Method of Storage System》 The present disclosure also relates to a control method for a power storage system when a power storage system is provided between a power conversion device that provides self-sufficient power generation from sunlight and a load, setting a drawn current value as an expected value received from the power conversion device, controlling the power conversion unit such that a current value obtained by subtracting a load current value supplied to the load from the drawn current value becomes a current value fed into a power conversion unit that charges a storage battery, which is a control method for a power storage system.

Advantages of the Invention

[0010] According to the present disclosure, it is possible to provide a power storage system and a control method thereof that can perform appropriate control without cooperating with a power conversion device of a solar power generation device.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

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Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0012] [Description of Embodiments of the Present Disclosure] The embodiments of the present disclosure mainly include at least the following.

[0013] (1) The present disclosure is a power storage system provided between a power conversion device that provides self-sufficient power generation by solar power generation and a load, and includes an AC circuit from an input terminal that receives the self-sufficient output to an output terminal to which the load is connected, a power conversion unit that is between the AC circuit and a storage battery and performs bidirectional power conversion between DC and AC, and a control unit that controls the power conversion unit. The control unit receives the setting of the drawn current value as an expected value received from the power conversion device, and controls the power conversion unit so that the current value obtained by subtracting the load current value supplied to the load from the drawn current value becomes the current value sent from the AC circuit to the power conversion unit.

[0014] In such a power storage system, while receiving power supply from an external power conversion device and supplying power to a load, control is performed so that the difference between the set drawn current value (fixed value) and the load current value becomes the current value (AC) for charging the storage battery. Therefore, the power storage system can perform appropriate control under the set drawn current value based on the set drawn current value without cooperating with an external power conversion device.

[0015] (2) In the power storage system of (1) above, when the load current value is greater than the drawn current value, the control unit may stop the operation of the power conversion unit. In this case, theoretically, the current value obtained by subtracting the load current value from the drawn current value becomes negative, but in reality, since the current (power) equal to or greater than the set drawn current value can be provided to the load by solar power generation, it is appropriate that the storage battery does not charge or discharge.

[0016] (3) In the power storage system of (1) or (2) above, a remote control device that is electrically connected to the control unit and has an operation reception function is provided, and the remote control device may set the drawn current value for the control unit. In this case, the drawn current value can be arbitrarily set from the remote control device.

[0017] (4) In the power storage system of (3) above, the drawn current value may be a value selected by the user from a plurality of candidate values displayed on the remote control device. In this case, the user can select and set the drawn current value from the candidate values as a reference.

[0018] (5) In any of the power supply systems of (1) to (4) above, when distortion exceeding a predetermined value occurs in the self-powered output from the power conversion device, the control unit can stop the operation of the power conversion unit and set it to a direct bypass state from the input end to the output end. Operating the power conversion unit of the power storage system may affect the operation of the power conversion device of the solar power generation and cause distortion in the self-powered output (voltage). In this case, if the power conversion device that detects the distortion stops, the power that can be generated cannot be utilized. Therefore, by stopping the power conversion unit of the power storage system and setting it to a bypass state, it is possible to suppress the stop of the power conversion device. As a result, the self-powered output from the solar power generation can be continuously utilized.

[0019] (6) In the power storage system of (5) above, if the distortion becomes less than the predetermined value, the control unit may operate the power conversion unit to charge the storage battery. Since the distortion may occur temporarily, if the distortion becomes less than the predetermined value, it is preferable to operate the power conversion unit and charge the storage battery in order to fully utilize the power of the solar power generation.

[0020] (7) In the power storage system of (5) above, when the battery is fully charged even if the distortion is less than the predetermined value, the control unit may continue the bypass state. In this case, since the battery cannot be further charged, it is preferable to supply power to the load by continuing the bypass state.

[0021] (8) In the power storage system of (3) above, the remote control device is connected via an electric communication line to a server that holds information regarding the weather, and the remote control device can also set the drawn current value based on the information acquired from the server. Since the power generation amount of solar power generation is greatly affected by the weather, an appropriate drawn current value can be set according to the weather.

[0022] (9) In the power storage system of (3) above, it may be provided with a sunshine recorder that detects the amount of solar radiation, and the remote control device may set the drawn current value based on the amount of solar radiation acquired from the sunshine recorder. Since the power generation amount can be estimated from the amount of solar radiation, an appropriate drawn current value can be set based on the estimated power generation amount.

[0023] (10) In the power storage system of (3) above, the remote control device acquires information on the past power generation amount from the power conversion device for solar power generation, and the remote control device may set the drawn current value based on the information. Since the current power generation amount can be estimated from the information on the past power generation amount, an appropriate drawn current value can be set based on the estimated power generation amount.

[0024] (11) In the power storage system of (3) above, it is provided with a mobile information terminal capable of communicating with the remote control device, and the remote control device accepts the setting of the drawn current value from the mobile information terminal, and when the set drawn current value is more than the equivalent value of the power generation amount of solar power generation, it may send information prompting a setting change to the mobile information terminal. In this case, the drawn current value can be set from the mobile information terminal. Also, when the set drawn current value is inappropriate, information prompting a setting change can be received, and the drawn current value can be changed. When the drawn current value is greater than the power generation amount of the solar power generation, the power conversion device of the solar power generation device will stop, but the stop can be avoided by changing the setting.

[0025] (12) The present disclosure is a control method for a power storage system when a power storage system is provided between a power conversion device that provides self-sufficient power by solar power generation and a load. The method sets a drawn current value as an expected value received from the power conversion device, and controls the power conversion unit so that the current value obtained by subtracting the load current value supplied to the load from the drawn current value becomes the current value sent to the power conversion unit that charges the storage battery.

[0026] According to such a control method for the power storage system, while receiving self-sufficient power from an external power conversion device and supplying power to the load, control is performed so that the difference between the set drawn current value (fixed value) and the load current value becomes the current value (alternating current) for charging the storage battery. Therefore, even without cooperation with an external power conversion device, the power storage system can perform appropriate control under the set drawn current value based on the set drawn current value.

[0027] [Details of Embodiments of the Present Disclosure] Hereinafter, a specific example of the power storage system of the present disclosure will be described with reference to the drawings.

[0028] [An Example of a Distributed Power System] FIG. 1 is a diagram showing a configuration example of a distributed power generation system for a consumer including a power storage system. In the figure, a solar power generation panel 2 is installed on the roof of consumer 1. The solar power generation panel 2 is connected to a power conversion device (power conditioner) 3. The output side of the power conversion device 3 is connected to a general load distribution board 4. The general load distribution board 4 is connected to a commercial power system 7 via a power selling electricity meter 5 and a power buying electricity meter 6. A power storage system 8 is connected to the general load distribution board 4 at AC100V / 200V. Further, the general load distribution board 4 is also connected to a dedicated load distribution board 9 at AC100V. So far, this is the connection in the normal state of the commercial power system 7.

[0029] When a power outage occurs in the commercial power system 7, the power conversion device 3 can disconnect itself from the commercial power system 7 and perform self-sustaining operation. During self-sustaining operation, a self-sustaining output at AC100V is provided to the power storage system 8. The power storage system 8 supplies AC100V to the dedicated load distribution board 9.

[0030] A remote control device 8r (which is also a part of the power storage system 8) is connected to the power storage system 8. The operation of the power storage system 8 can be performed by the remote control device 8r, and the operation status can also be displayed. The remote control device is connected to a router 10 via Wi-Fi (Wi-Fi is a registered trademark). The router is connected to the Internet.

[0031] 《Power Storage System》 Next, the power storage system 8 during self-sustaining operation will be described. FIG. 2 is a single-line connection diagram showing the power storage system 8 and its peripheral devices during self-sustaining operation. An input terminal 8 in which serves as an auxiliary input to the power storage system 8 receives the self-sustaining output of the power conversion device 3. A dedicated load distribution board 9 is connected to an output terminal 8 out of the power storage system 8. A dedicated load 11 that wants to continue power supply even during a power outage is connected to the dedicated load distribution board 9.

[0032] The power storage system 8 includes a voltage sensor 80, a switch 81, current sensors 82 and 83, a power conversion unit 84, a storage battery 85, a BMS (Battery Management System) 86, a control unit 87, and a remote control device 8r provided externally, and these are connected as shown in the figure. When the switch 81 is closed, an AC circuit 88 is formed from the input terminal 8 in to the output terminal 8 out . The voltage at the input terminal 8 in is detected by the voltage sensor 80. The current flowing through the specific load 11 is detected by the current sensor 82. The power conversion unit 84 is connected to a branch point 88j of the AC circuit 88. The current flowing between the branch point 88j and the power conversion unit 84 is detected by the current sensor 83. The power conversion unit 84 is a bidirectional inverter main circuit and can charge or discharge the storage battery 85.

[0033] The opening and closing of the switch 81 and the switching operation of the power conversion unit 84 are controlled by the control unit 87. The detection output of the voltage sensor 80, the detection outputs of the current sensors 82 and 83, and the monitoring signal of the BMS 86 are sent to the control unit 87. The BMS 86 sends the SOC (State of Charge) and other information of the storage battery 85 to the control unit 87. The control unit 87 is a computer system including, for example, a CPU and memories such as a ROM and a RAM (not shown). The necessary control functions are realized by the CPU executing software (computer program). The software is stored in the memory.

[0034] In the power storage system 8 configured as described above, when the voltage of the self-powered output from the power conversion device 3 is input to the power storage system 8, the voltage sensor 80 detects this, and the control unit 87 closes the switch 81. Let the input current value flowing from the power conversion device 3 into the power storage system 8 be Iin, the load current value flowing out from the power storage system 8 to the specific load 11 be Iout, and the current flowing from the branch point 88j to the power conversion unit 84, that is, the charge current command value, be Ibat.

[0035] In addition, the user can set the drawn current value Ipv as the predicted value of the alternating current drawn from the power conversion device 3 to the power storage system 8 in the remote control device 8r for the control unit 87. The values that can be selected as the setting values are, for example, one of the three values of 5A, 10A, and 14A. This is an example of stepwise values with the rated maximum value of the self-sufficient output of 1500W as the upper limit. Note that these setting values are only examples, and they may be set in finer steps.

[0036] Here, the input current value Iin (= Iout + Ibat) does not depend on the amount determined by the power conversion device 3, but rather on how much current is drawn. Also, since the maximum current (maximum power) that the power conversion device 3 can output depends on the solar irradiance, a constant value cannot always be ensured. Therefore, it is unclear to the power storage system 8 how much current can actually be drawn as the input current value Iin.

[0037] Therefore, assuming that the relationship between the charging current command value Ibat (effective value), the load current value Iout (effective value), and the drawn current value Ipv (effective value) as a provisional predicted value is given by the following equation (1) or (1a). When Ipv > Iout, Ibat = Ipv - Iout ···(1) When Ipv ≤ Iout, Ibat = 0 ···(1a) From equation (1), the current value obtained by subtracting the load current value from the set drawn current value becomes the charging current command value. However, when Ibat becomes a negative value in the calculation of equation (1), it means that a load current value exceeding the drawn current value can be provided as the self-sufficient output, so charging is not performed and the charging current command value Ibat = 0 is set according to equation (1a).

[0038] Figure 3 is a flowchart showing an example of how to obtain the charging current command value Ibat. The control unit 87 (Figure 2) first calculates the load current value Iout (effective value) based on the detection output of the current sensor 82 (Figure 2) in step S1. Next, the control unit 87 compares the drawn current value Ipv with the load current value Iout (step S2). If Ipv > Iout (YES), it proceeds to step S4. If Ipv ≤ Iout (NO), it proceeds to step S3.

[0039] When proceeding to step S4, the control unit 87 checks the SOC of the storage battery 85 from the information of the BMS86. If the SOC is 100% (or the upper limit value in the vicinity thereof), it proceeds to step S3. If charging is possible, it proceeds to step S5. In step S3, the charging current command value Ibat = 0 (no charging). In step S5, the charging current command value Ibat is set as Ibat = Ipv - Iout as shown in Equation (1) to charge the storage battery 85.

[0040] Figure 4 is a time chart showing an example of the changes in the load current value and the charging current command value. Assuming that the current of the self-powered output is a constant value and the drawn current value Ipv is set to 10 A. When the load current value is 0 A, the charging current command value Ibat is 10 A according to Equation (1). When the load current value increases to 7 A, the charging current command value Ibat becomes 3 A according to Equation (1). When the load current value increases to 13 A, the charging current command value Ibat becomes 0 A (charging stop) according to Equation (1a).

[0041] Figure 5 is a time chart showing another example of the changes in the load current value and the charging current command value. Assuming that the current of the self-powered output is a constant value and the drawn current value Ipv is set to 14 A. When the load current value is 0 A, the charging current command value Ibat is 14 A according to Equation (1). When the load current value increases to 7 A, the charging current command value Ibat becomes 7 A according to Equation (1). When the load current value increases to 13 A, the charging current command value Ibat becomes 1 A according to Equation (1).

[0042] Regarding the distortion of the input voltage In FIG. 2, when the power conversion device 3 operates independently and the power conversion unit 84 of the power storage system 8 is also charging, for example, due to the difference in the switching frequencies of the two, they may interfere with each other and the voltage of the independent output may be distorted. The distortion can be easily detected by comparing it with the ideal sinusoidal voltage by the voltage sensor 80 and the control unit 87 that receives its detection output.

[0043] FIG. 6(a) shows a case where power is supplied to the specific load 11 and the storage battery 85 is charged simultaneously by the independent output. In this state, if the control unit 87 detects that the voltage of the independent output has a distortion of a predetermined value or more, the control unit 87 stops charging and enters the state of (b). In the state of (b), the power conversion unit 84 stops switching, and the independent output becomes a bypass state that passes through the power storage system 8. Thereby, the distortion of the voltage of the independent output can be eliminated.

[0044] If the above distortion is left unattended, the power conversion device 3 itself will detect an abnormality in the output voltage and stop operating. When the operation stops, the switch 81 opens, and the power storage system 8 discharges the storage battery 85 to provide the independent output to the specific load 11. However, in this way, the independent output from solar power generation cannot be effectively utilized. It is a greater waste of energy not to be able to effectively utilize the energy of solar power generation than to stop charging the power storage system 8. Therefore, the power storage system 8 can suppress the operation stop of the power conversion device 3 by stopping charging and stably supply the independent output of solar power generation to the specific load 11.

[0045] After the charging is stopped, if the distortion becomes less than the predetermined value, the control unit 87 resumes the switching operation of the power conversion unit 84 and performs charging. Since the distortion may occur temporarily and not recur, it is preferable to actively perform charging from the viewpoint of effective utilization of energy. However, even if the distortion becomes less than the predetermined value, if the SOC of the storage battery 85 is in a fully charged state, the control unit 87 continues the bypass state.

[0046] 《Option Regarding the Method of Setting the Incoming Current Value》 As described above, the drawn-in current value Ipv can be manually set by the user on the remote control device 8r. However, the setting method is not limited to this. Other setting methods will be described below. Note that the following setting methods may be used in combination with each other.

[0047] FIG. 7 is a schematic diagram showing the setting of the drawn-in current value based on weather information. The remote control device 8r of the power storage system 8 is communicably connected to the weather information server 100 via the Internet. The power generation amount of solar power generation is affected by the weather. Therefore, the remote control device 8r can acquire the weather information at any time and change the setting of the drawn-in current value Ipv according to the assumed power generation amount from the weather information. For example, if the weather information is sunny, the maximum setting value can be used; if it is cloudy, the intermediate setting value can be used; and if it is rainy, the minimum setting value can be used. Also, considering the precipitation probability, the drawn-in current value can be set higher when the precipitation probability is low, and set lower when the precipitation probability is high.

[0048] FIG. 8 is a schematic diagram showing the setting of the drawn-in current value based on the solar radiation amount. The remote control device 8r of the power storage system 8 is connected to a pyranometer 200 provided near the solar power generation panel 2. The power generation amount of solar power generation is closely related to the solar radiation amount. Therefore, the remote control device 8r can acquire the solar radiation amount at any time and change the setting of the drawn-in current value Ipv according to the assumed power generation amount from the solar radiation amount. For example, if the solar radiation amount is divided into high level, medium level, and low level, and the above-mentioned values are used, it can be 14 A for high level, 10 A for medium level, and 5 A for low level.

[0049] The power generation amount of solar power generation can also be estimated from the information (history) of the past power generation amount. For example, when the output information can be acquired from the power conversion device 3 or the power meter 5 for selling electricity, the remote control device 8r stores the information of the past power generation amount. Then, based on the information of the past power generation amount, the remote control device 8r estimates the power generation amount from the year, month, and day, and sets the drawn-in current value (Ipv) corresponding to the power generation amount.

[0050] FIG. 9 is a schematic diagram showing the setting of the drawn current value using a mobile information terminal (e.g., a smartphone) 300. The remote control device 8r of the power storage system 8 can communicate with the mobile information terminal 300 via a router 10 (FIG. 1). On the screen of the dedicated application installed in the mobile information terminal 300, information including the current power generation amount, the drawn current value, and the load current value is displayed. When the user determines that it is necessary to change the setting of the drawn current value while viewing the screen on which these information are displayed, the user can change the set value from the mobile information terminal 300. Further, when the drawn current value exceeds the power generation amount equivalent value (current value corresponding to the power generation amount = generated power / voltage) estimated from the weather, solar radiation amount, etc., a signal prompting the setting change can be displayed from the remote control device 8r to the mobile information terminal 300.

[0051] Summary of the Disclosure The above disclosure can be generally expressed as follows.

[0052] In the power storage system 8 of the present disclosure, the control unit 87 receives the setting of the drawn current value (Ipv) as an expected value received from the power conversion device 3 of the solar power generation device, and from the drawn current value, the current value obtained by subtracting the load current value (Iout) supplied to the load is made to be the charging current command value (Ibat) sent from the AC circuit 88 to the power conversion unit 84, and controls the power conversion unit 84.

[0053] In such a power storage system 8, while receiving the supply of self - contained output from the external power conversion device 3 and supplying power to the specific load 11, control is performed such that the difference between the set drawn current value (Ipv, fixed value) and the load current value (Iout) becomes the charging current command value (Ibat, AC) for charging the storage battery 85. Therefore, the power storage system 8 can perform appropriate control under the set drawn current value (Ipv) without cooperating with the external power conversion device 3.

[0054] However, when the load current value (Iout) is greater than the drawn current value (Ipv), the control unit 87 stops the operation of the power conversion unit 84. In this case, theoretically, the current value obtained by subtracting the load current value (Iout) from the drawn current value (Ipv) becomes negative, but in reality, since it is possible to provide the specific load 11 with a current (power) equal to or greater than the set drawn current value (Ipv) through solar power generation, it is appropriate that the storage battery 85 neither charges nor discharges.

[0055] The setting of the drawn current value (Ipv) can be arbitrarily performed manually by the remote control device 8r. The user can select the drawn current value (Ipv) from a plurality of candidate values displayed on the remote control device 8r. In this case, the user can select and set the drawn current value from the reference candidate values.

[0056] The drawn current value (Ipv) can also be set (automatically set) based on other information, for example, as follows. (a) The remote control device 8r sets the drawn current value (Ipv) based on the information acquired from the weather information server 100 via the Internet. (b) The remote control device 8r sets the drawn current value (Ipv) based on the solar radiation amount acquired from the pyranometer 200. (c) The remote control device 8r sets the drawn current value (Ipv) based on the information on the past power generation amount.

[0057] It is also conceivable to communicate between the mobile information terminal 300 and the remote control device 8r. When the remote control device 8r receives the setting of the drawn current value (Ipv) from the mobile information terminal 300, it may send information prompting the mobile information terminal 300 to change the setting when the set drawn current value (Ipv) is greater than the equivalent value of the power generation amount of solar power generation.

[0058] In addition, when distortion equal to or greater than a predetermined value occurs in the self-sustained output from the power conversion device 3 of the photovoltaic power generation, it is preferable that the control unit 87 stops the operation of the power conversion unit 84. It should be avoided that the power conversion device 3 operating in a self-sustained manner stops operating due to the occurrence of distortion from the viewpoint of effective utilization of the generated power.

[0059] <Supplementary Note> It should be considered that the embodiments disclosed this time are illustrative in all respects and not restrictive. The scope of the present invention is shown by the scope of the claims, and it is intended that all modifications within the meaning and scope equivalent to the scope of the claims are included.

Explanation of Reference Numerals

[0060] 1 Consumer 2 Photovoltaic panel 3 Power conversion device 4 General load distribution board 5 Power meter for selling electricity 6 Power meter for purchasing electricity 7 Commercial power system 8 Energy storage system 8 in Input terminal 8 out Output terminal 8r Remote control device 9 Distribution board for specific load 10 Router 11 Specific load 80 Voltage sensor 81 Switch 82, 83 Current sensors 84 Power conversion unit 85 Storage battery 86 BMS 87 Control unit 88 AC circuit 88j Branch point 100 Weather information server 200 Pyranometer 300 Mobile information terminal

Claims

1. A power conversion device that provides self-sufficient power generation output, and a power storage system provided between the power conversion device and a load, an AC circuit extending from an input terminal that receives the self-sufficient output to an output terminal to which the load is connected, a power conversion unit that is between the AC circuit and a storage battery and performs bidirectional power conversion between DC and AC, a control unit that controls the power conversion unit, and a remote control device that is electrically connected to the control unit and has an operation reception function. The control unit: receives setting of a drawn current value as an expected value received from the power conversion device, controls the power conversion unit such that a current value obtained by subtracting a load current value supplied to the load from the drawn current value becomes a current value fed from the AC circuit to the power conversion unit, and the drawn current value is set for the control unit by the remote control device. A power storage system.

2. The power storage system according to claim 1, wherein when the load current value is greater than the drawn current value, the control unit stops the operation of the power conversion unit.

3. The power storage system according to claim 1 or claim 2, wherein the drawn current value is a value selected by a user from a plurality of candidate values displayed on the remote control device.

4. The power storage system according to any one of claims 1 to 3, wherein when distortion equal to or greater than a predetermined value occurs in the self-sufficient output from the power conversion device, the control unit stops the operation of the power conversion unit and sets a direct bypass state from the input terminal to the output terminal.

5. The power storage system according to claim 4, wherein when the distortion becomes less than the predetermined value, the control unit operates the power conversion unit to charge the storage battery.

6. The power storage system according to claim 4, wherein even if the distortion is less than the predetermined value and the storage battery is fully charged, the control unit continues the bypass state.

7. The remote control device is connected via an electric communication line to a server that holds information regarding the weather, The power storage system according to any one of claims 1 to 6, wherein the remote control device sets the drawn current value based on the information acquired from the server.

8. Equipped with a sunshine recorder that detects the amount of solar radiation, The power storage system according to any one of claims 1 to 6, wherein the remote control device sets the drawn current value based on the amount of solar radiation acquired from the sunshine recorder.

9. The remote control device acquires information on the past power generation amount from the power conversion device for solar power generation, The power storage system according to any one of claims 1 to 6, wherein the remote control device sets the drawn current value based on the information.

10. Equipped with a mobile information terminal capable of communicating with the remote control device, The remote control device accepts the setting of the drawn current value from the mobile information terminal, and when the set drawn current value is greater than the equivalent value of the power generation amount of solar power generation, sends information prompting a setting change to the mobile information terminal. The power storage system according to any one of claims 1 to 6.

11. A power storage system provided between a power conversion device that provides self-sufficient power output by solar power generation and a load, An AC circuit from the input terminal that receives the self-sufficient power output to the output terminal to which the load is connected, A power conversion unit that is between the AC circuit and the storage battery and performs bidirectional power conversion between DC and AC, A control unit that controls the power conversion unit, The control unit, Receiving a setting of an incoming current value as an expected value received from the power conversion device, Controlling the power conversion unit such that a current value obtained by subtracting a load current value supplied to the load from the incoming current value becomes a current value fed from the AC power line to the power conversion unit, The control unit further When distortion equal to or greater than a predetermined value occurs in the self-sustained output from the power conversion device, stopping the operation of the power conversion unit and setting a direct bypass state from the input terminal to the output terminal, When the distortion is less than the predetermined value and the storage battery is fully charged, continuing the bypass state Power storage system.

12. A control method for a power storage system when a power storage system is provided between a power conversion device that provides a self-sustained output by solar power generation and a load, Setting an incoming current value as an expected value received from the power conversion device by a remote control device having an operation reception function, Controlling the power conversion unit such that a current value obtained by subtracting a load current value supplied to the load from the incoming current value becomes a current value fed to a power conversion unit that charges a storage battery, Control method for a power storage system.

13. A control method for a power storage system when a power storage system is provided between a power conversion device that provides a self-sustained output by solar power generation and a load, Setting an incoming current value as an expected value received from the power conversion device, Controlling the power conversion unit such that a current value obtained by subtracting a load current value supplied to the load from the incoming current value becomes a current value fed to a power conversion unit that charges a storage battery, When distortion equal to or greater than a predetermined value occurs in the self-sustained output from the power conversion device, stopping the operation of the power conversion unit and setting a direct bypass state from an input terminal that receives the self-sustained output to an output terminal to which the load is connected, When the distortion is less than the predetermined value and the storage battery is fully charged, continuing the bypass state Control method for a power storage system.

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