JP7249561B2 - storage system - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electric storage system capable of setting a timer for discharge time.

In recent years, household power storage systems have become popular. In general, household power storage systems are introduced mainly for the purpose of backing up power during power outages (see, for example, Patent Literature 1). Many household power storage systems have a timer discharge function. The timer discharge function can be used to save electricity charges by charging with inexpensive late-night electricity and discharging in the morning, daytime, and night when electricity usage is high.

JP-A-8-154348

However, due to the timer discharge function, the momentary interruption that occurs when switching from grid power supply to storage battery power supply is not compatible with some home appliances. Cases have been reported. There are many complaints that the TV picture becomes unstable at a certain time every day.

The present disclosure has been made in view of such circumstances, and an object thereof is to provide an electricity storage system in which an instantaneous interruption at the start or end of timer discharge is suppressed.

In order to solve the above problems, a power storage system according to one aspect of the present invention includes a power storage unit, an inverter that converts DC power supplied from the power storage unit into AC power, and a current path between a power system and a load. a first switch inserted in a current path between a node on the current path at a position closer to the load than the first switch and an AC-side terminal of the inverter; a first current measuring unit that measures the current flowing from the electric power system to the load or the entire current flowing to the load; a second current measuring unit that measures the current flowing from the power storage unit to the node; controlling the inverter, the first switch and the second switch based on the first current value measured by the first current measuring unit and the second current value measured by the second current measuring unit and a control unit. The control unit controls the first switch to be in an ON state and the second switch to be in an OFF state in a normal state, and controls the first switch and the second switch to be in a preset discharge time period of the power storage unit. is turned on, and the inverter is controlled such that the ratio of the second current value to the first current value maintains a preset target value (the target value does not include 0).

According to the present disclosure, it is possible to suppress an instantaneous interruption at the start or end of timer discharge.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing the outline of the appearance of a power storage system according to an example; FIG. 2 is a perspective view showing a usage example of the power storage system of FIG. 1; It is a figure which shows the circuit structure of the electrical storage system which concerns on an Example. FIGS. 4A and 4B are diagrams summarizing the switch states of the power storage systems according to the comparative example and the example. FIGS. 5A and 5B are diagrams schematically showing current waveforms flowing through a specific load when switching from a normal state to a timer discharge state according to a comparative example and an example. 6 is a flow chart showing the flow of operations during timer discharge according to the embodiment; 9 is a flowchart showing additional control during timer discharge according to the embodiment; 6 is a flowchart showing the flow of operations during timer charging according to the embodiment; 4 is a flowchart showing automatic change processing of the target charging value; FIG. 5 is a diagram showing a circuit configuration of a power storage system according to Modification 1; FIG. 10 is a diagram showing a circuit configuration of a power storage system according to Modification 2;

FIG. 1 is a perspective view showing a schematic appearance of a power storage system 1 according to an embodiment. FIG. 2 is a perspective view showing a usage example of the power storage system 1 of FIG. The power storage system 1 according to the embodiment is a small power storage system with a power storage capacity of about 1 to 5 kWh. A small power storage system can be easily installed in a corner of a room or in an empty space. Also, by attaching casters, the user can move it around the room.

The power storage system 1 has an AC plug 1p for insertion into an indoor AC outlet 2c. By inserting the AC plug 1p into the indoor AC outlet 2c, power can be drawn from the commercial power system.

The power storage system 1 can supply power to the specific load 3 connected to the power storage system 1 . An AC outlet 1 c is provided on the front surface of the housing of the power storage system 1 . The user can provide power for the specific load 3 by inserting the AC plug 3p of the specific load 3 (the television 3t in the example shown in FIG. 2) into the AC outlet 1c of the power storage system 1 . For example, in the event of a power outage, by inserting the AC plug of the electrical equipment to be used into the AC outlet 1c, the electrical equipment can be used for a certain period of time.

Although not shown, it is also possible to connect the specific load 3 to the AC output terminal block of the power storage system 1 in advance by electrical wiring work. The specific load 3 is a load selected by the user, and can receive backup power supply from the power storage system 1 for a certain period of time in the event of a power failure. For example, lighting fixtures and the like are selected. Further, the specific load 3 is a load that is used to reduce electricity charges by utilizing timer charging and timer discharging.

An operation unit 1 o is provided on the front surface of the housing of the power storage system 1 . The operation unit 1o shown in FIG. 1 includes a touch panel display and physical buttons. The touch panel display displays information indicating the state of the power storage system 1, such as remaining capacity, charge amount, and discharge amount. The user can operate the operation unit 1o to set the operation mode and set the timer.

FIG. 3 is a diagram showing the circuit configuration of the power storage system 1 according to the embodiment. The power storage system 1 includes a power storage unit 10, a control unit 11, a discharging DC/AC inverter 12, a charging AC/DC converter 13, a first voltage measuring unit 14, a first current measuring unit 15, a second voltage measuring unit 16, It includes a second current measuring unit 17, a first switch SW1, a second switch SW2, and a third switch SW3.

Power storage unit 10 includes a storage battery and a monitoring unit. The storage battery is composed of a plurality of storage battery cells connected in series or in series-parallel. A lithium-ion battery, a nickel-metal hydride battery, a lead-acid battery, or the like can be used as the storage battery cell. In addition, you may use capacitors, such as an electric double layer capacitor and a lithium ion capacitor, instead of a storage battery. In this specification, an example is assumed in which a plurality of lithium ion storage battery cells are connected to form a storage battery with a storage capacity of 1 to 5 kWh. The monitoring unit monitors the states (for example, voltage, current, temperature) of the plurality of storage battery cells, and transmits monitoring data of the plurality of storage battery cells to the control unit 11 via the communication line.

A commercial power system (hereinafter simply referred to as system 2 ) and specific load 3 are electrically connected via first current path P<b>1 in power storage system 1 . A first switch SW is inserted in the first current path P1.

A discharge DC/AC inverter 12 is connected between a first node N1 on a first current path P1 at a position closer to the specific load 3 than the first switch SW1 and the power storage unit 10 . A second switch SW2 is inserted in a second current path P2 between the first node N1 on the first current path P1 and the AC-side terminal of the DC/AC inverter 12 for discharge.

DC/AC inverter 12 for discharge converts the DC power supplied from power storage unit 10 into AC power, and outputs the AC power to first current path P1. The discharge DC/AC inverter 12 includes a bridge circuit in which four or six switching elements are bridge-connected. In the case of single-phase alternating current, it is composed of four pieces, and in the case of three-phase alternating current, it is composed of six pieces. For example, an IGBT (Insulated Gate Bipolar Transistor) or a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) can be used as the switching element. The control unit 11 can adjust the output current or the output voltage of the discharge DC/AC inverter 12 by controlling the duty ratios of the plurality of switching elements forming the bridge circuit.

Charging AC/DC converter 13 is connected between power storage unit 10 and second node N2 on first current path P1 at a position closer to system 2 than first switch SW1. A third switch SW3 is inserted in a third current path P3 between the second node N2 on the first current path P1 and the AC-side terminal of the AC/DC converter 13 for charging.

Charging AC/DC converter 13 converts AC power supplied from system 2 into DC power, and outputs the DC power to power storage unit 10 . Charging AC/DC converter 13 includes a bridge circuit in which four or six switching elements are bridge-connected. Control unit 11 can adjust the output current or output voltage of charging AC/DC converter 13 by controlling the duty ratios of the plurality of switching elements that constitute the bridge circuit. For example, CC-CV charging can be performed.

A relay or a semiconductor switch can be used for the first switch SW1 to the third switch SW3 described above.

The first voltage measurement unit 14 measures the voltage (system voltage) of the first current path P<b>1 and outputs it to the control unit 11 . The first voltage measurement unit 14 can be configured by, for example, a resistance voltage dividing circuit and a differential amplifier. The first current measuring unit 15 is installed at a position closer to the specific load 3 than the first node N1 on the first current path P1. The first current measurement unit 15 measures the entire current flowing through the specific load 3 and outputs it to the control unit 11 . The first current measurement unit 15 can be configured by, for example, a CT sensor.

The second voltage measurement unit 16 measures the voltage of the second current path P2 and outputs the voltage to the control unit 11 . The second voltage measurement unit 16 can be configured by, for example, a resistance voltage dividing circuit and a differential amplifier. The second current measurement unit 17 is installed on the second current path P2. Second current measurement unit 17 measures the current flowing from power storage unit 10 to first node N<b>1 and outputs the current to control unit 11 . The second current measurement unit 17 can be configured by, for example, a CT sensor.

The control unit 11 can be realized by cooperation of hardware resources and software resources, or only by hardware resources. Analog devices, microcomputers, DSPs, ROMs, RAMs, ASICs, FPGAs, and other LSIs can be used as hardware resources. Programs such as firmware can be used as software resources.

The control unit 11 receives storage battery monitoring data from the monitoring unit of the power storage unit 10 . The control unit 11 acquires the voltage value of the first current path P1 from the first voltage measurement unit 14, and acquires the value of the current flowing through the specific load 3 (hereinafter referred to as the first current value) from the first current measurement unit 15. do. The control unit 11 acquires the voltage value of the second current path P2 from the second voltage measurement unit 16, and the output current value of the discharge DC/AC inverter 12 from the second current measurement unit 17 (hereinafter referred to as the second current value). ).

The control unit 11 acquires information input by the user through the operation unit 1o. The user can set the operation mode of the power storage system 1 from the operation unit 1o. The user can select either economy mode or power storage mode.

Economic mode is a mode in which the battery is operated according to the set charge/discharge time. In this mode, the battery is charged during the time period when electricity charges are discounted (from 23:00 to 7:00 the next day at major electric power companies in Japan) and discharged during the time periods when the electricity charges are not discounted. The user can set the charging time period and the discharging time period. The economy mode is a mode whose main purpose is to reduce the metered portion of the electricity bill.

The power storage mode is a mode in which the power storage capacity of the power storage system 1 is always maintained at the charging target value. After charging is completed, it waits in preparation for a power outage. The power storage mode is a mode mainly intended for backup during a power failure. For the remainder of this specification, it will be assumed that economy mode has been selected.

The control unit 11 can connect to various servers on the Internet 5 via the router device 4 . The control unit 11 and the router device 4 are connected by wireless communication. For example, communication conforming to WiFi (registered trademark) and Bluetooth (registered trademark) is performed. In addition, you may connect with a wire between both.

The control unit 11 receives information from a power transmission and distribution company server, a DR (Demand Response) server, a VPP (Virtual Power Plant) company server, a server of the manufacturer of the power storage system 1, a weather company server, etc., which are connected to the Internet 5. can receive. For example, it receives a charge command or a discharge command from a power transmission and distribution company server, a DR server, or a VPP server. Note that the configuration in which the control unit 11 performs external communication via the router device 4 is not essential, and a stand-alone system may be used.

Based on the acquired information, the control unit 11 controls the discharging DC/AC inverter 12, the charging AC/DC converter 13, the first switch SW1 to the third switch SW3.

FIGS. 4A and 4B are diagrams summarizing switch states of the power storage system 1 according to the comparative example and the example. FIG. 4(a) shows the switch state according to the comparative example, and FIG. 4(b) shows the switch state according to the embodiment.

Normally, the control unit 11 controls the first switch SW1 to be on, the second switch SW2 to be off, and the third switch SW3 to be off. In this state, power is supplied to the specific load 3 only from the grid 2 . Switch control during normal operation is the same between the comparative example and the embodiment.

During timer charging, the control unit 11 turns on the first switch SW1, turns off the second switch SW2, and turns on the third switch SW3. In this state, power is supplied to the specific load 3 only from the grid 2 . Power storage unit 10 is charged with power supplied from system 2 . Switch control during timer charging is also the same between the comparative example and the embodiment.

At the time of timer discharge, switch control differs between the comparative example and the embodiment. In the comparative example, the control unit 11 turns off the first switch SW1, turns on the second switch SW2, and turns off the third switch SW3. In this state, power is supplied to the specific load 3 only from the power storage system 1 . In the embodiment, the control unit 11 controls the first switch SW1 to the ON state, the second switch SW2 to the ON state, and the third switch SW3 to the OFF state. In this state, power is supplied to the specific load 3 from both the grid 2 and the power storage system 1 .

In the embodiment, during timer discharge, the controller 11 causes the discharge DC/AC inverter 12 to output AC power with a voltage synchronized with the phase and frequency of the system voltage (synchronization mode). The phase and frequency of the system voltage can be detected based on the zero-cross timing of the system voltage acquired from the first voltage measurement section 14 .

In the embodiment, during timer discharge, the control unit 11 presets the current ratio R of the second current value acquired from the second current measurement unit 17 to the first current value acquired from the first current measurement unit 15. The discharging DC/AC inverter 12 is controlled so as to maintain the set target value T (0<T<1). Specifically, when the current ratio R is lower than the target value T, the controller 11 increases the duty ratios of the switching elements included in the discharge DC/AC inverter 12 . Conversely, when the current ratio R is higher than the target value T, the controller 11 reduces the duty ratios of the switching elements included in the discharge DC/AC inverter 12 .

As the target value T is set higher, the contribution of the current discharged from the power storage system 1 to the total current supplied to the specific load 3 increases, and the contribution of the current supplied from the grid 2 decreases. The greater the contribution of the current discharged from the power storage system 1, the greater the effect of saving electricity charges. However, since the capacity visible from the specific load 3 becomes smaller, the voltage and frequency tend to fluctuate. The designer sets the target value T in consideration of the power storage capacity of the power storage unit 10, specifications of electronic components used in the power storage system 1, and the like.

When the system 2 fails, the controller 11 turns off the first switch SW1, turns on the second switch SW2, and turns off the third switch SW3. In this state, power is supplied to the specific load 3 only from the power storage system 1 . Switch control at the time of power failure is the same between the comparative example and the working example. During a power outage in the system 2, the control unit 11 causes the discharge DC/AC inverter 12 to output AC power of a voltage having a phase and frequency generated independently (asynchronous mode).

FIGS. 5A and 5B are diagrams schematically showing current waveforms flowing through the specific load 3 when the normal state is switched to the timer discharge state, according to the comparative example and the example. FIG. 5(a) shows the current waveform according to the comparative example, and FIG. 5(b) shows the current waveform according to the example. In the comparative example, an instantaneous interruption occurs at the timing of switching from the normal state to the timer discharge state. On the other hand, in the embodiment, the switching from the normal state to the timer discharge state is performed smoothly without an instantaneous interruption.

FIG. 6 is a flowchart showing the flow of operations during timer discharge according to the embodiment. When a predetermined time (for example, 0.5 to 10 minutes) before the timer discharge start time (Y in S10), the control unit 11 turns on the second switch SW2 (S11). After that, when the timer discharge start time arrives (Y of S12), the controller 11 causes the discharge DC/AC inverter 12 to start current output (S13). At that time, the control unit 11 controls the discharge DC/AC inverter 12 so that the current ratio R gradually increases from an initial value lower than the target value T to the target value T. FIG. The initial value may be zero, or may be a value between zero and the target value T. The value of the initial value and the rate of increase from the initial value to the target value T are set by the designer. After the current ratio R reaches the target value T, the controller 11 controls the discharge DC/AC inverter 12 so that the current ratio R maintains the target value T (S14).

When the end time of the timer discharge comes (Y of S15), the controller 11 causes the discharge DC/AC inverter 12 to end the current output (S16). At that time, the control unit 11 controls the discharge DC/AC inverter 12 so that the current ratio R gradually decreases from the target value T to zero. The rate of decrease from the target value T to zero is set by the designer. After a predetermined time (for example, 5 to 30 seconds) after the end time of the timer discharge (Y in S17), the controller 11 turns off the second switch SW2 (S18).

FIG. 7 is a flowchart showing additional control during timer discharge according to the embodiment. At a predetermined time before the timer discharge start time (Y of S20), the control unit 11 starts acquiring the first current value from the first current measuring unit 15 (S21). The control unit 11 calculates the variation rate of the acquired first current value (S22). For example, the standard deviation of peak-to-peak values of the first current value over a predetermined period of time may be calculated.

When the calculated variation rate of the first current value exceeds the set value (Y in S23), the control unit 11 causes the discharge DC/AC inverter 12 to temporarily stop the current output (S24). The process transitions to step S21. When the variation rate of the first current value does not exceed the set value (N of S23), the control section 11 corrects the target value T according to the variation rate of the first current value (S25). Specifically, a correction to lower the target value T is applied as the variation rate of the first current value increases. A map or function in which the values of the set values and the correction coefficients of the variation rate and the target value T are associated with each other are set by the designer. When the end time of the timer discharge arrives (Y of S26), the additional control is terminated. During execution of the timer discharge (N of S26), the processes of steps S21 to S25 are repeatedly executed.

Note that the additional control shown in FIG. 7 is optional and not essential. When only the basic control shown in FIG. 6 is executed, the target value T is fixed, and discharge from the power storage system 1 is not interrupted during the period of timer discharge.

FIG. 8 is a flowchart showing the flow of operations during timer charging according to the embodiment. When the timer charging start time arrives (Y of S30), the controller 11 turns on the third switch SW3 (S31). The control unit 11 causes the charging AC/DC converter 13 to start the charging operation at a current rate at which charging ends at the set charging end time (S32).

When the SOC (State Of Charge) of the storage battery in power storage unit 10 reaches the charging target value (Y in S33), control unit 11 terminates the operation of charging AC/DC converter 13 (S34), and the third switch. SW3 is turned off (S35). Control unit 11 estimates the SOC of the storage battery based on the voltage and current of the storage battery cell notified from the monitoring unit in power storage unit 10 . The SOC can be estimated, for example, by a current integration method or an OCV (Open Circuit Voltage) method.

In general, storage batteries have a lifespan due to storage deterioration and cycle deterioration. Storage deterioration is deterioration that progresses over time according to the temperature of the storage battery at each point in time and the SOC at each point in time. It progresses over time regardless of whether charging/discharging is in progress. Storage deterioration occurs mainly due to the formation of a film (SEI (Solid Electrolyte Interphase) film) on the negative electrode. Storage deterioration depends on the SOC and temperature at each time point. Generally, the higher the SOC at each time point and the higher the temperature at each time point, the higher the storage deterioration rate.

Cycle deterioration is deterioration that progresses as the number of times of charging and discharging increases. Cycle deterioration is mainly caused by cracking or peeling due to expansion or contraction of the active material. Cycle degradation depends on current rate, SOC range used, and temperature. Generally, the higher the current rate, the wider the SOC range used, and the higher the temperature, the higher the cycling degradation rate.

In both the power storage mode and the economy mode, charging the storage battery to the full charge capacity (SOC=100%) makes it possible to secure a large amount of backup capacity in the event of a power failure. However, from the viewpoint of suppressing deterioration of the storage battery, it is desirable that the SOC of the storage battery is low. The designer sets the default charging target value in consideration of both requests. For example, in the SOC range of 70% to 90%, the default charging target value is set at a position where cost performance is as good as possible in consideration of the slope of the storage deterioration rate curve.

FIG. 9 is a flowchart showing automatic change processing of the charging target value. If the target charging value is specified by the user (Y of S40), the control unit 11 sets the target charging value to the value specified by the user (S41). If the charging target value is not specified by the user (N of S40), the control unit 11 sets the charging target value to a default value (eg, 80%) (S42).

When the control unit 11 receives the weather warning information from the weather operator server connected to the Internet 5 (Y in S43), the control unit 11 changes the charging target value to 100% (S44). Weather warning information is information based on advisories or warnings, for example, regarding heavy rain, floods, landslides, storm surges, and storms. Since the risk of a power failure occurring due to worsening weather conditions increases, the control unit 11 switches to a mode in which the storage battery is charged to the full charge capacity.

When the control unit 11 receives the cancellation information of the weather alert information from the weather operator server (Y in S45), the control unit 11 transitions to step S40 and returns to the original value. Note that in step S43, the control unit 11 also changes the charging target value to 100% when the rolling blackout information is received from the power transmission and distribution business operator server. When the rolling blackout ends, the charging target value is restored to the original value.

As described above, according to this embodiment, the power supply from the system 2 to the specific load 3 is maintained at a constant rate without interrupting the power supply from the system 2 to the specific load 3 during timer discharge. Accordingly, it is possible to prevent an instantaneous interruption from occurring at the start or end of the timer discharge. Further, at the start or end of timer discharge, the current ratio R is gradually changed from the initial value to the target value T, or the current ratio R is gradually changed from the target value T to zero. can smooth the current change over time. In addition, by adaptively changing the current ratio R based on the rate of change of the current flowing through the specific load 3, it is possible to moderate fluctuations in voltage and frequency that accompany load fluctuations.

Also, by switching the charging target rate according to the risk of occurrence of a power outage, it is possible to satisfy both the request for suppressing the deterioration of the storage battery and the request for securing the backup capacity.

The present disclosure has been described above based on the embodiments. Those skilled in the art will easily understand that the embodiments are illustrative, and that various modifications can be made to the combination of each component and each treatment process, and that such modifications are within the scope of the present disclosure. be.

FIG. 10 is a diagram showing a circuit configuration of a power storage system 1 according to Modification 1. As shown in FIG. In the circuit configuration shown in FIG. 3, the first current measurement unit 15 is installed at a position closer to the specific load 3 than the first node N1 on the first current path P1. In Modification 1, the first current measurement unit 15 is installed at a position between the first switch SW1 and the first node N1 on the first current path P1. In this case, the first current value measured by the first current measuring unit 15 is a value indicating the current flowing from the system 2 to the specific load 3 . In this case, the target value T (0<T) may be defined by (second current value/first current value), and the target value T (0<T<1) may be defined by (second current value/(first It may be defined by (1 current value+second current value)).

FIG. 11 is a diagram showing a circuit configuration of a power storage system 1 according to Modification 2. As shown in FIG. In the above embodiment, an example in which power is supplied from the power storage system 1 to the specific load 3 selected by the user has been described. Modification 2 will explain an example in which power is supplied to a general load 3 a instead of the specific load 3 . The general load 3 a is a concept including all indoor loads to which power is supplied from the grid 2 .

In this configuration, the first current path P<b>1 that is the main line exists outside the housing of the power storage system 1 . Therefore, it is necessary to install the first voltage measurement unit 14 and the first current measurement unit 15 outside the housing of the power storage system 1 . Wire connection between the first voltage measurement unit 14 and the control unit 11 and between the first current measurement unit 15 and the control unit 11 complicates the wiring. When the user moves the power storage system 1, those wires become an obstacle.

In Modified Example 2, the control unit 11 wirelessly communicates from the smart meter 6 installed at the inlet from the system 2 to the indoors, and obtains the voltage value (system voltage value) and current value (first current value) of the first current path P1. value). For example, it is acquired using WiFi (registered trademark), Bluetooth (registered trademark), or specified low-power radio using the 920 MHz band. In addition, you may acquire using the power line communication (PLC:Power Line Communication) using the 1st electric current path|route P1. As described above, it is possible to construct a system in which signal lines are eliminated even in Modification 2. FIG. Note that the voltage value and current value of the first current path P1 may be obtained from a smart distribution board instead of the smart meter 6 .

In the circuit configuration shown in FIG. 3, the discharging DC/AC inverter 12 and the charging AC/DC converter 13 are provided separately, but they may be integrated. For example, the discharging DC/AC inverter 12 may be changed to a bidirectional inverter, and the charging AC/DC converter 13 and the third switch SW3 may be omitted.

In addition, the embodiment may be specified by the following items.

[Item 1]
a power storage unit (10);
an inverter (12) for converting DC power supplied from the power storage unit (10) into AC power;
a first switch (SW1) inserted in a current path (P1) between the power system (2) and the load (3);
on the current path (P2) between the node (N1) on the current path (P1) at the position closer to the load (3) than the first switch (SW1) and the AC side terminal of the inverter (12). a second switch (SW2) to be inserted;
a first current measuring unit (15) for measuring the current flowing from the electric power system (2) to the load (3) or the entire current flowing to the load (3);
a second current measuring unit (17) for measuring the current flowing from the power storage unit (10) to the node (N1);
Based on the first current value measured by the first current measuring unit (15) and the second current value measured by the second current measuring unit (17), the inverter (12), the first A control unit (11) that controls the switch (SW1) and the second switch (SW2),
The control unit (11)
In a normal state, the first switch (SW1) is controlled to be ON and the second switch (SW2) is controlled to be OFF;
The first switch (SW1) and the second switch (SW2) are controlled to be on in a predetermined discharge time period of the storage unit (10), and the ratio of the second current value to the first current value is adjusted. A power storage system (1) characterized by controlling the inverter (12) such that the ratio maintains a preset target value (the target value does not include 0).
According to this, it is possible to suppress an instantaneous interruption at the start or end of the timer discharge.
[Item 2]
The control unit (11)
The power storage system (1) according to item 1, wherein the second switch (SW2) is turned on a predetermined time before the start time of the discharge period.
According to this, it is possible to contribute to suppression of current fluctuation at the start of timer discharge.
[Item 3]
The control unit (11)
Item 1 or 2, wherein the inverter (12) is controlled so that the ratio gradually increases from a value lower than the target value to the target value at the start of the discharge time period. An electrical storage system (1) as described.
According to this, it is possible to contribute to suppression of current fluctuation at the start of timer discharge.
[Item 4]
The control unit (11)
4. The power storage system (1) according to any one of items 1 to 3, wherein the second switch (SW2) is turned off after a predetermined time from the end time of the discharge period.
According to this, it is possible to contribute to suppression of current fluctuation at the end of timer discharge.
[Item 5]
The control unit
5. The method according to any one of items 1 to 4, wherein the inverter (12) is controlled so that the ratio gradually decreases from the target value to zero at the end of the discharge period. An electrical storage system (1) as described.
According to this, it is possible to contribute to suppression of current fluctuation at the end of timer discharge.
[Item 6]
The control unit
6. The power storage system (1) according to any one of items 1 to 5, wherein the target value is lowered as the variation rate of the first current value increases in the discharge time period.
According to this, fluctuations in the voltage or frequency of the power supplied to the load (3) can be suppressed.
[Item 7]
The control unit
7. The method according to any one of items 1 to 6, wherein current output from the inverter (12) is suspended when the rate of change of the first current value exceeds a set value in the discharge time period. An electrical storage system (1) as described.
According to this, fluctuations in the voltage or frequency of the power supplied to the load (3) can be suppressed.
[Item 8]
The control unit
5. The method according to any one of items 1 to 4, wherein the first switch (SW1) is turned off and the second switch (SW2) is turned on in the event of a power failure in the power system (2). An electrical storage system (1) as described.
According to this, the electric power of load (3) can be backed up at the time of a power failure.
[Item 9]
The control unit
causing the inverter (12) to output AC power having a voltage synchronized with the phase and frequency of the system voltage during the discharge time period;
The power storage system (1) according to item 8, wherein the inverter (12) is caused to output AC power having a voltage having a phase and frequency generated independently during a power failure in the power system (2). ).
According to this, the power backup function at the time of power failure and the timer discharge function can be operated appropriately.
[Item 10]
10. The power storage system (1) according to any one of items 1 to 9, wherein the load (3) is a specific load (3) selected by a user.
According to this, it is possible to construct a compact, wiring-less power storage system (1) capable of backing up the specific load (3).

1 power storage system 1o operation unit 1c AC outlet 1p AC plug 2 systems 2c AC outlet 3 specific load 3t television 3p AC plug 3a general load 4 router device 5 internet 6 smart meter 10 Power storage unit 11 control unit 12 discharging DC/AC inverter 13 charging AC/DC converter 14 first voltage measuring unit 15 first current measuring unit 16 second voltage measuring unit 17 second current measuring unit , SW1 first switch, SW2 second switch, SW3 third switch, P1 first current path, P2 second current path, P3 third current path.

Claims (10)

a power storage unit;
an inverter that converts the DC power supplied from the power storage unit into AC power;
a first switch inserted in a current path between the power system and the load;
a second switch inserted in a current path between a node on the current path located closer to the load than the first switch and an AC-side terminal of the inverter;
a first current measuring unit that measures the current flowing from the power system to the load or the entire current flowing to the load;
a second current measurement unit that measures the current flowing from the power storage unit to the node;
controlling the inverter, the first switch and the second switch based on the first current value measured by the first current measuring unit and the second current value measured by the second current measuring unit a control unit;
The control unit
controlling the first switch to be on and the second switch to be off under normal conditions;
The first switch and the second switch are controlled to be on during a preset discharge time period of the power storage unit, and the ratio of the second current value to the first current value is set to a preset target value. (the target value does not include 0). The control unit
2. The power storage system according to claim 1, wherein said second switch is turned on a predetermined time before the start time of said discharge period. The control unit
3. The inverter according to claim 1, wherein the inverter is controlled such that the ratio gradually increases from a value lower than the target value to the target value at the start of the discharge period. storage system. The control unit
4. The power storage system according to any one of claims 1 to 3, wherein the second switch is turned off after a predetermined time from the end time of the discharge period. The control unit
5. The inverter according to any one of claims 1 to 4, wherein the inverter is controlled such that the ratio gradually decreases from the target value to zero at the end of the discharge period. storage system. The control unit
The power storage system according to any one of claims 1 to 5, wherein the target value is lowered as the variation rate of the first current value increases in the discharge time period. The control unit
7. The current output from the inverter is suspended when the variation rate of the first current value exceeds a set value in the discharge time period. storage system. The control unit
5. The power storage system according to any one of claims 1 to 4, wherein the first switch is turned off and the second switch is turned on when the power system fails. The control unit
causing the inverter to output AC power having a voltage synchronized with the phase and frequency of the system voltage during the discharge time period;
9. The power storage system according to claim 8, wherein, in the event of a power failure in the electric power system, the inverter is caused to output alternating current power of a voltage having a phase and a frequency generated independently. The power storage system according to any one of claims 1 to 9, wherein the load is a specific load selected by a user.

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