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, determines a peak value of a load current supplied to the load as an absolute value, and controls the power conversion unit so that the peak value of a current fed from the AC electric path to the power conversion unit does not exceed a current value obtained by subtracting the peak value of the load current from a value of double the square root of the lead-in current value.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] The number of small-scale electricity consumers, such as ordinary homes, who install solar power generation equipment is increasing. Such solar power generation equipment can be connected to the commercial power grid via a power conversion device and sell the electricity. In addition, during a power outage, the power conversion device can be disconnected from the commercial power grid and operated independently, so that electricity can be supplied by independent output to specific loads that are desired to be used during the power outage.

[0003] Furthermore, in recent years, distributed power supply systems that incorporate a storage battery-equipped power storage system in addition to a solar power generation device are becoming more widespread (see, for example, Patent Document 1). During a power outage, the system supplies power to a specific load within the consumer's facility through independent output, and if there is a surplus of power that can be generated, the storage battery can be charged, making it possible to effectively use the generated power without waste. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-35236 Summary of the Invention [Problem to be solved by the invention]

[0005] When introducing a new distributed power supply system that combines a solar power generation system with a storage battery, it is possible to connect the solar power generation panel and the storage battery to a single power conversion device with hybrid functions and perform integrated advanced control. However, when a customer who already has a solar power generation system adds a storage system later while effectively utilizing the existing equipment, the solar power generation system and the storage system will be controlled separately. In this case, it is unclear from the storage system's perspective how much independent output can be obtained from the solar power generation system.

[0006] An object of the present disclosure is to provide a power storage system and a control method thereof that can perform appropriate control without linking with a power conversion device of a solar power generation system. [Means for solving the problem]

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

[0008] Energy storage system The present disclosure provides a power storage system provided between a power conversion device that provides independent output by solar power generation and a load, an AC circuit extending from an input terminal for receiving the independent output to an output terminal to which the load is connected; a power conversion unit that is disposed 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 is Accepting a setting of a sink current value as a predicted value to be received from the power conversion device; A peak value of a load current supplied to the load is calculated as an absolute value; Controlling the power conversion unit so that a peak value of a current sent from the AC circuit to the power conversion unit does not exceed a current value obtained by subtracting the peak value of the load current from a value that is √2 times the incoming current value. It is a power storage system.

[0009] "Method for controlling power storage system" The present disclosure also provides a method for controlling a power storage system when the power storage system is provided between a power conversion device that provides an independent output by photovoltaic power generation and a load, comprising: A current draw value is set as a predicted value to be received from the power conversion device; A peak value of a load current supplied to the load is calculated as an absolute value; Controlling the power conversion unit so that a peak value of a current fed to the power conversion unit for charging the storage battery does not exceed a current value obtained by subtracting the peak value of the load current from a value that is √2 times the draw current value. A method for controlling a power storage system. Effect 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 linking with a power conversion device of a solar power generation system. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing a configuration example of a distributed power supply system of a consumer including a power storage system. [Diagram 2] FIG. 2 is a single-line connection diagram showing the power storage system and its peripheral devices during independent operation. [Diagram 3] FIG. 3 is a flowchart showing an example of a method for determining the peak value of the charging current command value. [Figure 4] For reference, FIG. 4 is a waveform diagram showing an example of what happens when control is performed based on effective values ​​rather than peak values ​​and the load is a nonlinear load. [Diagram 5] FIG. 5 is a waveform diagram showing an example of a state in which the load is a nonlinear load under peak value-conscious control according to the present disclosure. [Figure 6] FIG. 6 is a time chart showing an example of changes in the load current value and the charging current command value. [Figure 7]FIG. 7 is a time chart showing another example of changes in the load current value and the charging current command value. [Figure 8] In Fig. 8, (a) shows a case where the independent output is used to supply power to a specific load and charge the storage battery at the same time, while (b) shows a bypass state where the control unit stops charging and the independent output passes directly through the storage battery system. [Figure 9] FIG. 9 is a schematic diagram showing the setting of the lead current value based on weather information. [Figure 10] FIG. 10 is a schematic diagram showing the setting of the draw current value based on the amount of solar radiation. [Figure 11] FIG. 11 is a schematic diagram showing the setting of the lead-in current value using a mobile information terminal (smartphone). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] [Description of the embodiments of the present disclosure] The gist of the present disclosure includes at least the following.

[0013] (1) The present disclosure relates to a power storage system provided between a power conversion device that provides an independent output by solar power generation and a load, the power storage system including: an AC circuit extending from an input terminal that receives the independent output to an output terminal to which the load is connected; a power conversion unit that is located 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, wherein the control unit receives a setting of a draw current value as a predicted value to be received from the power conversion device, calculates an absolute value of a peak value of a load current to be supplied to the load, and controls the power conversion unit so that the peak value of a current sent from the AC circuit to the power conversion unit does not exceed a current value obtained by subtracting the peak value of the load current from a value multiplied by √2 of the draw current value.

[0014] In such a power storage system, while receiving an independent output from an external power conversion device and supplying power to a load, the difference between the value multiplied by √2 of the set draw current value (fixed value) and the peak value of the load current is controlled to be the peak value of the current (AC) for charging the storage battery. Therefore, the power storage system can perform appropriate control based on the draw current value set by itself without linking with an external power conversion device. Furthermore, even in the case of a nonlinear load, control can be performed to suppress the stop of the external power conversion device.

[0015] (2) In the energy storage system of (1), when the peak value of the load current is greater than a value that is √2 times the value of the draw current, the control unit may stop operation of the power conversion unit. In this case, theoretically the current value obtained by subtracting the peak value of the load current from √2 times the draw current value will be negative, but in reality, the solar power generation will be able to provide the load with a current (power) greater than or equal to the set draw current value, so it is appropriate not to charge or discharge the storage battery.

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

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

[0018] (5) In any of the power supply systems (1) to (4), when distortion of a predetermined value or more occurs in the isolated output from the power conversion device, the control unit can stop operation of the power conversion unit and establish a bypass state directly from the input terminal to the output terminal. Operating the power conversion unit of the energy storage system may affect the operation of the power conversion device of the solar power generation, causing distortion in the independent 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 energy storage system and putting it into a bypass state, it is possible to prevent the power conversion device from stopping. This allows the independent output from the solar power generation to be used continuously.

[0019] (6) In the power storage system of (5) above, when the distortion becomes less than the predetermined value, the control unit may operate the power conversion unit to charge the storage battery. Since distortion may occur temporarily, it is preferable to operate the power conversion unit and charge the storage battery when the distortion falls below a predetermined value in order to make full use of the power generated by solar power.

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

[0021] (8) In the energy storage system of (3), the remote control device is connected to a server that stores weather information via a telecommunications line, and the remote control device can also set the draw current value based on the information obtained from the server. Since the amount of power generated by solar power generation is greatly affected by the weather, it is possible to set an appropriate draw current value depending on the weather.

[0022] (9) The power storage system according to (3) may further include an actinometer that detects an amount of solar radiation, and the remote control device may set the draw current value based on the amount of solar radiation obtained from the actinometer. Since the amount of power generation can be estimated from the amount of solar radiation, an appropriate draw current value can be set based on the estimated amount of power generation.

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

[0024] (11) The energy storage system of (3) may further include a mobile information terminal capable of communicating with the remote control device, and the remote control device may receive a setting of the draw current value from the mobile information terminal and, if the set draw current value is greater than a value equivalent to the amount of power generated by solar power generation, may send information to the mobile information terminal prompting the mobile information terminal to change the setting. In this case, the draw current value can be set from the mobile information terminal. If the set draw current value is not appropriate, information is received prompting a change in the setting, and the draw current value can be changed. If the draw current value is greater than the amount of power generated by the solar power generation system, the power conversion device of the solar power generation system will stop, but this can be avoided by changing the setting.

[0025] (12) The present disclosure relates to a control method for a power storage system when a power storage system is provided between a power conversion device that provides independent output through solar power generation and a load, the control method for a power storage system including: setting an input current value as an expected value to be received from the power conversion device; calculating an absolute peak value of a load current to be supplied to the load; and controlling the power conversion unit so that the peak value of a current sent to a power conversion unit that charges a storage battery does not exceed a current value obtained by subtracting the peak value of the load current from a value multiplied by √2 of the input current value.

[0026] According to such a control method for a power storage system, while receiving an independent output from an external power conversion device and supplying power to a load, control is performed so that the difference between the value multiplied by √2 of the set draw current value (fixed value) and the peak value of the load current becomes the peak value of the current (AC) for charging the storage battery. Therefore, the power storage system can perform appropriate control based on the draw current value set by itself without linking with an external power conversion device. Furthermore, even in the case of a nonlinear load, control can be performed to suppress the stop of the external power conversion device.

[0027] [Details of the embodiment of the present disclosure] Hereinafter, specific examples of the power storage system according to 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 an example of the configuration of a distributed power supply system of a consumer including a power storage system. In the diagram, a photovoltaic power generation panel 2 is installed on the roof of a consumer 1. The photovoltaic 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 energy meter 5 and a power buying energy meter 6. A power storage system 8 is connected to the general load distribution board 4 at AC 100V / 200V. The general load distribution board 4 is also connected to a specific load distribution board 9 at AC 100V. Up to this point, the connections of the commercial power system 7 are normal.

[0029] In the event of a power outage in the commercial power grid 7, the power conversion device 3 can disconnect itself from the commercial power grid 7 and perform independent operation. During independent operation, an independent output of AC 100V is provided to the power storage system 8. The power storage system 8 supplies AC 100V to a specific load distribution board 9.

[0030] A remote control device 8r (also a part of the power storage system 8) is connected to the power storage system 8. The remote control device 8r can be used to operate the power storage system 8 and also to display the operating state. The remote control device is connected to the router 10 via Wi-Fi (Wi-Fi is a registered trademark). The router is connected to the Internet.

[0031] Energy storage system Next, the electricity storage system 8 during independent operation will be described. FIG. 2 is a single-line connection diagram showing the power storage system 8 and its peripheral devices during independent operation. in The independent output of the power conversion device 3 is input to the output terminal 8 of the power storage system 8. out A specific load distribution board 9 is connected to the specific load. A specific load 11 to which it is desired to continue supplying power even in the event of a power outage is connected to the specific 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 an external remote control device 8r, all of which are connected as shown in the figure. in From output end 8 out An AC current path 88 is formed leading to the input terminal 8 inThe voltage of the specific load 11 is detected by a voltage sensor 80. The current flowing through the specific load 11 is detected by a current sensor 82. The power conversion unit 84 is connected to a branch point 88j of an AC current circuit 88. The current flowing between the branch point 88j and the power conversion unit 84 is detected by a 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 a control unit 87. The detection output of the voltage sensor 80, the detection outputs of the current sensors 82 and 83, and a monitoring signal of the BMS 86 are sent to the control unit 87. The BMS 86 sends the SOC (State of Charge) of the storage battery 85 and other information to the control unit 87. The control unit 87 is a computer system including, for example, a CPU and memories such as ROM and RAM (not shown), and the CPU executes software (computer programs) to realize the necessary control functions. The software is stored in the memory.

[0034] In the power storage system 8 configured as described above, when the voltage of the independent 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. The input current value flowing from the power conversion device 3 to the power storage system 8 is Iin, the load current value flowing from the power storage system 8 to the specific load 11 is Iout, and the current flowing from the branch point 88j to the power conversion unit 84, i.e., the charging current command value, is Ibat.

[0035] Furthermore, the user can set, in the remote control device 8r, a draw current value Ipv as a predicted value of the AC current drawn from the power conversion device 3 to the power storage system 8 for the control unit 87. The set value that can be selected is, for example, one of three values: 5 A, 10 A, and 14 A. This is an example of a stepped value with the maximum rated value of the independent output of 1500 W as the upper limit. Note that these set values ​​are merely examples, and the values ​​may be set in finer steps.

[0036] Here, the input current value Iin (=Iout+Ibat) is not an amount determined by the power conversion device 3, but depends on how much current is drawn. In addition, the maximum current (maximum power) that the power conversion device 3 can output depends on the amount of solar radiation, so it is not always possible to ensure a constant value. Therefore, it is unknown to the power storage system 8 how much current can actually be drawn as the input current value Iin.

[0037] Therefore, using the incoming current value Ipv as a provisional estimated value, the relationship between the peak value Ibat_peak, which is the √2 times value of the charging current command value Ibat (effective value), the peak value Iout_peak, which is the √2 times value of the load current value Iout as an effective value, and the charging current command value Ipv (effective value) is expressed as the following formula (1) or (1a). Note that each value is an absolute value. When Ipv×√2>Iout_peak, Ibat_peak=Ipv×√2-Iout_peak ···(1) When Ipv×√2≦Iout_peak, Ibat_peak=0 (1a) According to formula (1), the current value obtained by subtracting the peak value of the load current from a value that is √2 times the set draw current value becomes the upper limit of the peak value of the charge current command value. The charge current command value Ibat (effective value) is (1 / √2) of the peak value Ibat_peak. However, when Ibat_peak becomes a negative value in the calculation of formula (1), this means that a peak value of the load current that exceeds √2 times the draw current value is being provided as an independent output, so charging is not performed, and the peak value of the charge current command value Ibat_peak is set to 0 according to formula (1a).

[0038] FIG. 3 is a flow chart showing an example of how to obtain the peak value of the charging current command value Ibat. First, in step S1, the control unit 87 (FIG. 2) updates the absolute value of the instantaneous value of the load current to the larger value in sequence between the zero crossing and the next zero crossing based on the detection output of the current sensor 82 (FIG. 2), and sets the maximum value as the peak value Iout_peak. This calculation may be performed after filtering such as moving average to remove noise. Also, it may be performed in one cycle or multiple cycles. Next, the control unit 87 compares the value of √2 times the incoming current value Ipv with the peak value Iout_peak of the load current (step S2), and if Ipv×√2>Iout_peak (YES), the process proceeds to step S4, and if Ipv×√2≦Iout_peak (NO), the process proceeds to step S3.

[0039] When the process proceeds to step S4, the control unit 87 checks the SOC of the storage battery 85 from the information from the BMS 86, and if the SOC is 100% (or an upper limit value close to that), the process proceeds to step S3, and if charging is possible, the process proceeds to step S5. In step S3, the peak value Ibat_peak of the charging current command value is set to 0 (no charging). In step S5, the peak value Ibat_peak of the charging current command value is set to Ibat_peak=Ipv×√2-Iout_peak according to equation (1), and the storage battery 85 is charged.

[0040] For reference, Figure 4 is a waveform diagram showing an example of what happens when control is performed with an effective value in mind, rather than a peak value as described above, and the load is nonlinear. The horizontal axis is time, which is common to (a) to (d). (a) shows the actual current waveform when the incoming current value is Ipv. Since the incoming current value Ipv is an effective value, the peak value (wave height value) of the current waveform is Ipv × √2 in absolute value.

[0041] FIG. 4(b) is a waveform diagram showing an example of the load current Iout flowing through a nonlinear load. In this case, the peak value is Iout_peak in absolute value. Since the waveform is not a continuous sine wave, the effective value is relatively small. If it is considered that the charging current command value Ibat can be increased accordingly, the waveform will be as shown in (c), for example. In this case, the peak value is Ibat_peak in absolute value.

[0042] However, when the instantaneous values ​​of (b) and (c) are superimposed, the input current value Iin from the power electronics device 3 becomes the waveform of (d). At times t1 and t2, the peak value of Iin exceeds the peak value of the incoming current value Ipv. In this case, the power electronics device 3 may stop. In other words, while the effective value level does not indicate a stop, the peak value level may result in an unnecessary stop.

[0043] Figure 5 is a waveform diagram showing an example of the state that occurs when the load is a nonlinear load under peak value-conscious control as shown in formula (1). The horizontal axis is time, which is common to (a) to (d). (a) shows the actual current waveform when the incoming current value is Ipv. Since the incoming current value Ipv is an effective value, the peak value (wave height value) of the current waveform is Ipv × √2 in absolute value.

[0044] FIG. 5(b) is a waveform diagram showing an example of the load current Iout flowing through a nonlinear load. In this case, the peak value is Iout_peak in absolute value. From equation (1), the peak value Ibat_peak of the charging current command value is Ipv×√2-Iout_peak. FIG. 5(c) is a waveform diagram of this charging current command value Ibat. In this case, the peak value is Ibat_peak in absolute value. As is clear from a comparison with FIG. 4(c), the charging current command value Ibat is suppressed.

[0045] The input current value Iin from the power conversion device 3 has a waveform (d) which is a superposition of the instantaneous values ​​(b) and (c) in Fig. 5. Although peak values ​​of Iin occur at times t1 and t2, they do not exceed the peak value of the incoming current value Ipv. Therefore, unnecessary shutdowns of the power conversion device 3 are suppressed.

[0046] Next, Fig. 6 is a time chart showing an example of changes in the load current value and the charging current command value. It is assumed that the current of the independent output is a constant value, and the drawing current value Ipv is set to 10A (peak value 14.1A). When the load current value is 0A, the peak value Ibat_peak of the charging current command value is 14.1A according to formula (1). When the peak value Iout_peak of the load current increases to 9.9A, the peak value Ibat_peak of the charging current command value becomes 4.2A according to formula (1). When the peak value Iout_peak of the load current increases to 18.4A, the peak value Ibat_peak of the charging current command value becomes 0A (charging is stopped) according to formula (1a).

[0047] Fig. 7 is a time chart showing another example of the change in the load current value and the charging current command value. It is assumed that the current of the independent output is a constant value and the drawing current value Ipv is set to 14A (peak value 19.8A). When the load current value is 0A, the peak value Ibat_peak of the charging current command value is 19.8A according to formula (1). When the peak value Iout_peak of the load current increases to 9.9A, the peak value Ibat_peak of the charging current command value becomes 9.9A according to formula (1). When the peak value of the load current increases to 18.4A, the charging current command value Ibat_peak becomes 1.4A according to formula (1).

[0048] <Input voltage distortion> 2, when the power conversion device 3 is operating independently and the power conversion unit 84 of the power storage system 8 is also charging, for example, the difference in switching frequency between the two may cause mutual interference, resulting in distortion of the voltage of the independent output. The distortion can be easily detected by the voltage sensor 80 and the control unit 87 that receives the detection output from the voltage sensor 80, by comparing it with an ideal sine wave voltage.

[0049] 8(a) shows a case where the independent output is simultaneously supplying power to the specific load 11 and charging the storage battery 85. In this state, if the control unit 87 detects that the voltage of the independent output is distorted by a predetermined value or more, the control unit 87 stops charging and switches to state (b). In state (b), the power conversion unit 84 stops switching, and the independent output goes into a bypass state where it passes directly through the storage system 8. This makes it possible to eliminate distortion in the voltage of the independent output.

[0050] If the above distortion is left unchecked, the power conversion device 3 itself will detect an abnormality in the output voltage and stop operation. When operation stops, the switch 81 opens and the power storage system 8 discharges the storage battery 85 to provide independent output to the specific load 11. However, this does not allow effective use of the independent output from solar power generation. There is more energy wasted by not being able to effectively use the energy of solar power generation than by stopping charging of the power storage system 8. Therefore, by stopping charging, the power storage system 8 can prevent the power conversion device 3 from stopping operation and can stably supply independent output from solar power generation to the specific load 11.

[0051] After charging is stopped, if the distortion falls below a predetermined value, the control unit 87 restarts the switching operation of the power conversion unit 84 and performs charging. Since distortion may occur temporarily and not reoccur, it is preferable to perform charging proactively from the viewpoint of effective use of energy. However, even if the distortion falls below 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.

[0052] <Options for setting the lead-in current value> As described above, the lead-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.

[0053] FIG. 9 is a schematic diagram showing the setting of the draw-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 amount of power generated by photovoltaic power generation is affected by the weather. Therefore, the remote control device 8r can acquire weather information at any time and change the setting of the draw-in current value Ipv according to the amount of power generated estimated from the weather information. For example, if the weather information is sunny, the maximum setting value can be set, if it is cloudy, the intermediate setting value can be set, and if it is raining, the minimum setting value can be set. In addition, taking into account the probability of precipitation, the draw-in current value can be set higher when the probability of precipitation is low, and lower when the probability of precipitation is high.

[0054] FIG. 10 is a schematic diagram showing the setting of the draw current value based on the amount of solar radiation. The remote control device 8r of the power storage system 8 is connected to a solar radiation meter 200 provided near the solar power generation panel 2. The amount of power generated by solar power generation is closely related to the amount of solar radiation. Therefore, the remote control device 8r can acquire the amount of solar radiation at any time and change the setting of the draw current value Ipv according to the amount of power generated estimated from the amount of solar radiation. For example, the amount of solar radiation can be divided into high level, medium level, and low level, and the above-mentioned values ​​can be 14A for the high level, 10A for the medium level, and 5A for the low level.

[0055] The amount of power generated by photovoltaic power generation can also be estimated from information (history) on the amount of power generated in the past. For example, when output information can be acquired from the power conversion device 3 or the power meter 5 for selling power, the remote control device 8r stores information on the amount of power generated in the past. Then, the remote control device 8r estimates the amount of power generated from the date based on the information on the amount of power generated in the past, and sets the incoming current value (Ipv) appropriate for the amount of power generated.

[0056] FIG. 11 is a schematic diagram showing the setting of the draw 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 the router 10 (FIG. 1). The screen of a dedicated application installed on the mobile information terminal 300 displays information including the current power generation amount, the draw current value, and the load current value. When the user judges that the setting of the draw current value needs to be changed while viewing the screen displaying this information, the user can change the setting value from the mobile information terminal 300. In addition, when the draw current value exceeds the power generation amount equivalent value (current value equivalent to the power generation amount=generated power / voltage) estimated from the weather, the amount of solar radiation, etc., the remote control device 8r can display a signal to the mobile information terminal 300 to prompt the mobile information terminal 300 to change the setting.

[0057] Summary of disclosure The above disclosure can be generalized and expressed as follows.

[0058] In the energy storage system 8 of the present disclosure, the control unit 87 receives a setting of the incoming current value (Ipv) as an expected value received from the power conversion device 3 of the solar power generation device, and controls the power conversion unit 84 so that the peak value (Ibat_peak) of the charging current command value (Ibat) sent from the AC circuit 88 to the power conversion unit 84 does not exceed a current value obtained by subtracting the peak value (Iout_peak) of the load current (Iout) supplied to the load from a value √2 times the incoming current value.

[0059] In such a power storage system 8, while receiving an independent output from the external power conversion device 3 and supplying power to the specific load 11, the difference between the value multiplied by √2 of the set draw current value (Ipv, fixed value) and the peak value (Iout_peak) of the load current (Iout) becomes the peak value (Ibat_peak) of 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 draw current value (Ipv) set by itself without linking with the external power conversion device 3. Furthermore, even in the case of a nonlinear load, control can be performed to suppress the stop of the power conversion device 3.

[0060] However, when the peak value (Iout_peak) of the load current (Iout) is greater than the value of √2 times the draw current value (Ipv), the control unit 87 stops the operation of the power conversion unit 84. In this case, the current value obtained by subtracting the peak value (Iout_peak) of the load current (Iout) from the value of √2 times the draw current value (Ipv) is theoretically negative, but in reality, a current (power) equal to or greater than the set draw current value (Ipv) is being provided to the specific load 11 by photovoltaic power generation, so it is appropriate not to charge or discharge the storage battery 85.

[0061] The setting of the lead-in current value (Ipv) can be manually set arbitrarily by the remote control device 8r. The user can select the lead-in 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 lead-in current value from the candidate values ​​that serve as a guideline.

[0062] The incoming 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 incoming current value (Ipv) based on information acquired from the weather information server 100 via the Internet. (b) The remote control device 8r sets the incoming current value (Ipv) based on the amount of solar radiation obtained from the actinometer 200. (c) The remote control device 8r sets the incoming current value (Ipv) based on information on the amount of power generated in the past.

[0063] It is also possible for communication to occur between the mobile information terminal 300 and the remote control device 8r. The remote control device 8r accepts the setting of the incoming current value (Ipv) from the mobile information terminal 300, and may also send information to the mobile information terminal 300 prompting it to change the setting if the set incoming current value (Ipv) is greater than the value equivalent to the amount of power generated by solar power generation.

[0064] When distortion of a predetermined value or more occurs in the independent output from the photovoltaic power generation power conversion device 3, it is preferable that the control unit 87 stops the operation of the power conversion unit 84. From the viewpoint of effective use of generated power, it should be avoided that the independent operating power conversion device 3 stops operation due to the occurrence of distortion.

[0065] 《Addendum》 The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, and it is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0066] 1 Consumer 2. Solar panels 3. Power conversion device 4 General load distribution board 5. Electricity meter for selling electricity 6 Electricity meter for power purchase 7 Commercial power system 8. Energy Storage System 8 in Input Terminal 8 out Output Terminal 8r Remote control device 9. Specific load distribution board 10 Router 11 Specific load 80 Voltage Sensor 81 Switch 82,83 Current sensors 84 Power conversion section 85 Storage battery 86 BMS 87 Control Unit 88 AC line 88j Junction 100 Weather Information Server 200 pyranometer 300 Mobile information terminal

Claims

1. A power storage system provided between a power conversion device that provides independent output by photovoltaic power generation and a load, an AC circuit extending from an input terminal for receiving the independent output to an output terminal to which the load is connected; a power conversion unit that is disposed 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 is Accepting a setting of a sink current value as a predicted value to be received from the power conversion device; A peak value of a load current supplied to the load is calculated as an absolute value; Controlling the power conversion unit so that a peak value of a current sent from the AC circuit to the power conversion unit does not exceed a current value obtained by subtracting the peak value of the load current from a value √2 times the incoming current value. Energy storage system.

2. The power storage system according to claim 1 , wherein the control unit stops operation of the power conversion unit when the peak value of the load current is greater than a value that is √2 times the draw current value.

3. a remote control device electrically connected to the control unit and having an operation receiving function; The power storage system according to claim 1 or 2, wherein the draw current value is set for the control unit by the remote control device.

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

5. 5. The energy storage system according to claim 1, wherein, when a distortion of a predetermined value or more occurs in an independent output from the power conversion device, the control unit stops operation of the power conversion unit and establishes a bypass state in which a direct connection is established from the input terminal to the output terminal.

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

7. The power storage system according to claim 5 , wherein when the storage battery is fully charged even if the distortion becomes less than the predetermined value, the control unit continues the bypass state.

8. The remote control device is connected to a server that stores weather information via an electric communication line, The power storage system according to claim 3 , wherein the remote control device sets the draw current value based on the information acquired from the server.

9. Equipped with a pyranometer to detect the amount of solar radiation, The power storage system according to claim 3 , wherein the remote control device sets the draw current value based on the amount of solar radiation acquired from the actinometer.

10. the remote control device acquires information on past power generation amount from the power conversion device for solar power generation, The power storage system according to claim 3 , wherein the remote control device sets the draw current value based on the information.

11. a mobile information terminal capable of communicating with the remote control device, 4. The power storage system according to claim 3, wherein the remote control device accepts a setting of the draw current value from the mobile information terminal, and sends information to the mobile information terminal to prompt the mobile information terminal to change the setting if the set draw current value is greater than a value equivalent to a power generation amount of solar power generation.

12. A method for controlling a power storage system in a case where the power storage system is provided between a power conversion device that provides an independent output by photovoltaic power generation and a load, comprising the steps of: A current draw value is set as a predicted value to be received from the power conversion device; A peak value of a load current supplied to the load is calculated as an absolute value; Controlling the power conversion unit so that a peak value of a current fed to the power conversion unit for charging the storage battery does not exceed a current value obtained by subtracting the peak value of the load current from a value that is √2 times the value of the incoming current. A method for controlling an energy storage system.

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