JP2014121151A - Power storage system and power supply system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage system and power supply system having the same, capable of significantly charging a power storage device, which is charged with received power from a commercial power system, and capable of completely reducing the received power from the commercial power system.SOLUTION: A control section (8) acquires received power from received power detection means (61), determines charging power on the basis of a difference value between a preset power value and the received power when the received power is smaller than a predetermined preset power value, and controls a power conditioner (2) for power storage to charge a power storage device (1) with the charging power.

Description

  The present invention relates to a power storage system including a storage battery that supplies power to a load, and relates to a power supply system including the power storage system.

  In recent years, there has been an increase in the introduction of a power supply system including a power source that is different from a commercial power system as a power supply system for a power system (referred to as a load system) to which a load is connected. In such a power supply system having a separate power source, a part of the power consumption (demand power) of the load system is covered by the power from the power source, and the power supply from the commercial power system is reduced. ing. In such a power supply system, charging is performed during a period when the demand power of the load system is small, and discharging is performed during a period when the demand power of the load system increases.

  Next, a power supply system using a conventional storage battery will be described. The power supply system includes a storage battery, a power conditioner that adjusts charging / discharging of the storage battery, a power distribution unit that adjusts the flow of power, a power detection unit that detects received power from the commercial power system, and a control unit. I have.

  In the power supply system, an upper limit of received power (average value) from the commercial power system is set in advance (hereinafter referred to as set power), and when the received power exceeds set power, the storage battery Supply power to the load system. That is, in the power supply system, power is drawn from the storage battery so that the received power from the commercial power system does not exceed the set power.

  For example, when the demand power of the load system increases and the received power exceeds the set power, the control unit controls the power conditioner and causes the power distribution unit to output power due to the discharge of the storage battery. The power distribution unit supplies the load system with power that is a combination of the received power from the commercial power system and the discharge power of the storage battery. Further, the control unit controls the power conditioner when the demand power of the load system is small, that is, when the received power from the commercial power system is smaller than the set power (for example, at midnight). Then, the storage battery is charged (see, for example, Japanese Patent Laid-Open No. 2008-306832).

  As described above, in the power supply system, the received power from the commercial power system is suppressed so as not to exceed the set power (so-called peak cut).

  Currently, in Japan, the power supplier can use the power usage fee (the amount of received power received from the commercial power grid) by adding the basic fee (contract fee) determined in advance and the metered fee according to the power usage. ) Has been determined. The basic charge is determined based on the maximum peak (hereinafter referred to as peak power) of received power in the past year. In other words, even if it is a short period in the past year, if there is a prominent power usage record (maximum peak power), it becomes a basic charge based on the maximum peak power for one year and is set high. Since the peak cut can be performed by using the power supply system, the maximum peak power can be reduced and the basic charge can be reduced.

  And in the said electric power supply system, when surplus electric power (the electric power of the part which exceeds the demand electric power of the supply electric power of the said commercial power system) is charged to the said storage battery, and when the said surplus electric power reduces after that, from the said storage battery By assisting the received power with the discharged power, the maximum amount of power supplied by the commercial power system can be suppressed, and the occurrence of large-scale power outages and further expansion of facilities in preparation for large power outages can be suppressed. Is also possible.

JP 2008-306832 A

  The power storage system disclosed in Japanese Patent Application Laid-Open No. 2008-306832 has a configuration in which the storage battery is charged in a time zone in which the demand power of the load system decreases. However, the demand power of the load system to which the power supply system is connected does not always decrease in the same time zone, and the time when the supply power of the commercial power system decreases does not necessarily match, and charging of the storage battery and the load There is a risk that reliable peak cut may not be performed by supplying power to the grid.

  Further, in the case of a system including a plurality of storage batteries in parallel, charging of the storage batteries provided in parallel may cause the received power of the commercial power to exceed the set power, and reliable peak cut may not be performed. .

  Therefore, the present invention includes a power storage device that is charged with received power from a commercial power system, can sufficiently charge the power storage device, and can reliably reduce the received power from the commercial power system. An object is to provide a system and a power supply system including the system.

  In order to achieve the above object, the present invention provides a power storage system that supplies power to a load and is connected between a power receiving unit to which a commercial power system is connected and the load, and charges and discharges the power storage device. A power conditioner for power storage to be adjusted; a received power detection means for detecting received power from the commercial power system; and a control unit, wherein the control unit acquires the received power from the received power detection means, and the received power Is smaller than a preset set power value, the charging power is determined based on a difference value between the set power value and the received power, and the power storage power conditioner is charged with the charged power. A power storage system characterized by controlling the power supply is provided.

  According to this configuration, when charging the power storage device, it is possible to finely adjust the charge to the power storage device by switching the charging power value to the power storage device. Moreover, it can suppress that the received electric power from the said commercial power grid exceeds the preset value.

  From the above, it is possible to suppress the received power from the commercial power system from exceeding a predetermined set power value while securing the remaining charge of the power storage device. The set power value may be a contract power value contracted between an electric supplier and an electric consumer, or a value obtained by multiplying the contract power value by a safety factor smaller than 1. It may be used. When a delay in the operation of the control unit occurs, it is preferable that the set power value is smaller than the contract power value.

  The above configuration further includes a charge amount detection unit that detects the charge power and sends the result to the control unit, and the control unit determines the charge power based on a difference value between the set power value and the received power. The power storage power conditioner may be controlled so as to have the value obtained.

  In the above configuration, when the charging power value determined by the difference value between the set power value and the received power is larger than the maximum value of the charging power, the control unit sets the power storage device at the maximum value of the charging power. The power storage power conditioner may be controlled so as to charge the battery.

  In the above configuration, the power storage device includes a plurality of power storage systems in which the power storage device and the power conditioner for power storage are connected in series, and is connected in parallel to the power receiving unit, and the control unit includes the power storage device in each power storage system. Each power storage power conditioner may be controlled such that the sum of the amount of power for charging is smaller than the charging power value determined by the difference value between the set power value and the received power.

  The present invention provides a power supply system in which power is supplied to the load, and a power generation system that reversely flows power to the commercial power system and a power storage system configured as described above are connected in parallel to the power receiving unit. To do.

  A method for controlling a power storage device, the step of obtaining received power, the step of comparing the received power with a preset power value, and the setting when the received power is smaller than the set power value. A step of calculating a difference value between the power value and the received power, a step of determining a charging power value based on the calculated difference value, and a step of charging the power storage device with the charging power.

  The said structure WHEREIN: The process of adjusting charge amount may be included so that the said charging power value may become a value determined based on the difference value of the said setting power value and the said received power.

  In the above configuration, the method includes a step of comparing a charging power value determined by a difference value between the set power value and the received power and a maximum value of the charging power, wherein the charging power value is greater than the maximum value of the charging power. A step of setting the charging power value to the maximum value of the charging power when the charging power value is large.

  According to the present invention, it is possible to provide a power storage system that includes a storage battery that is charged with received power from a commercial power system and that can reliably reduce the received power from the commercial power system, and a power supply system using the same. it can.

It is a block diagram of an example of the electric power supply system provided with the electrical storage system concerning this invention. It is a figure which shows the state which is drive | operating the electrical storage system of FIG. 1 in grid connection operation mode. It is a figure which shows the state which is drive | operating the electrical storage system of FIG. 1 in charge operation mode. It is a figure which shows the state which is drive | operating the electrical storage system of FIG. It is a figure which shows the state which is drive | operating the electrical storage system of FIG. 1 in self-sustained operation mode. It is a flowchart for determining an operation mode. It is a flowchart which shows the determination process of the electrical storage amount in the electrical storage system concerning this invention. It is a block diagram which shows the other example of the electrical storage system concerning this invention. It is a block diagram of the electric power supply system provided with the electrical storage system concerning this invention.

(First embodiment)
Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram of an example of a power supply system provided with a power storage system according to the present invention. The power storage system shown in FIG. 1 includes a storage battery 1, and reduces the received power from the commercial power system CS by supplying the stored power (discharge power) of the storage battery 1 to the load system LS.

  Here, the commercial power system CS is a power supply network by a power supplier such as a power company. The load system LS is divided into a normal load system LSs and a special load system LSp. The normal load system LSs is a load such as an electric lamp and a washing machine, and is a system to which loads that do not greatly hinder each device and life even when power supply is stopped. On the other hand, the special load system LSp is a system to which loads such as refrigerators, servers, and the like that greatly hinder each device and life are connected when power supply is stopped.

  As shown in FIG. 1, the power storage system A includes a storage battery 1 (power storage device), a storage battery power conditioner 2 (power storage power conditioner), and a control unit 8. The power supply system including the power storage system A further includes a power distribution unit 5, a power reception unit 6, and a switch 7. In the following description, the storage battery 1 and the storage battery power conditioner 2 may be collectively referred to as a storage system BS.

  The details of the power storage system A will be described with reference to the drawings. The storage battery 1 is a secondary storage battery that can be repeatedly discharged and charged. Examples of the storage battery 1 include a lithium secondary battery, a nickel hydrogen battery, a nickel cadmium battery, and a lead storage battery. The discharge power (output) from the storage battery 1 is direct current. A breaker 11 is attached to a wiring connected to an input / output terminal (not shown) of the storage battery 1. This breaker 11 is always ON, and when the breaker 11 is ON, the storage battery 1 is discharged and charged. Moreover, the charge amount sensor 12 which detects the present charge amount (remaining charge amount) of the storage battery 1 is provided. The charge amount sensor 12 is connected to the control unit 8 and transmits the current charge amount (for example, electric energy) of the storage battery 1 to the control unit 8.

  The storage battery 1 is connected to the power distribution unit 5 via a storage battery power conditioner 2. The storage battery power conditioner 2 includes a bidirectional DC / DC converter 21, a bidirectional inverter (bidirectional DC / AC converter) 22, a protection relay 23, and an interconnection relay 24. In the storage battery power conditioner 2, a bidirectional DC / DC converter 21, a bidirectional inverter 22, a protection relay 23, and an interconnection relay 24 are connected in this order from the storage battery 1 side.

  Discharge power (output) of the storage battery 1 flows into the bidirectional DC / DC converter 21 of the storage battery power conditioner 2. The bidirectional DC / DC converter 21 is disposed between the storage battery 1 and the bidirectional inverter 22. The bidirectional DC / DC converter 21 arbitrarily converts the output voltage of the storage battery 1 and outputs it to the bidirectional inverter 22, and arbitrarily converts the electric power from the bidirectional inverter 22 and outputs it to the storage battery 1. The bidirectional inverter 22 converts the direct current from the storage battery 1 into alternating current, and also converts the alternating current supplied from the commercial power system CS into direct current. The bidirectional DC / DC converter 21 and the bidirectional inverter 22 are well known in the art and will not be described in detail.

  The protection relay 23 is a switch that is always ON, and is turned OFF when a large current flows, when an abnormality occurs in the storage battery 1 or the storage battery power conditioner 2, and the circuits, devices, and the like that constitute the storage battery power conditioner 2 Protect.

  The interconnection relay 24 is a switch that is turned on when the output of the storage battery 1 is supplied to the power distribution unit 5. The interconnection relay 24 is normally OFF. Then, when the demand power of the load system LS increases and the received power from the commercial power system CS exceeds a predetermined set power value, the interconnection relay 24 is turned on. Then, the electric power of the storage battery 1 is added to the received power from the commercial power system CS and supplied to the load system LS. Note that the protection relay 23 and the interconnection relay 24 may be arranged in reverse.

  The storage battery power conditioner 2 includes a self-supporting relay 25 connected between the bidirectional inverter 43 and the protection relay 23. The self-supporting relay 25 is connected to the switch 7 arranged outside the power conditioner 2 for the storage battery. The self-supporting relay 25 is a relay that constitutes a circuit that directly supplies the output power of the storage battery 1 to the special load system LSp, and is a circuit that is always OFF.

  The storage battery power conditioner 2 includes a power detection sensor 26 that detects power (voltage, current, etc.) flowing between the bidirectional DC / DC converter 21 and the bidirectional inverter 22.

  The storage battery power conditioner 2 includes a control circuit 20 for controlling the bidirectional DC / DC converter 21, the bidirectional inverter 22, the protection relay 23, the interconnection relay 24, the self-supporting relay 25, and the power detection sensor 26. The control circuit 20 may be configured to control the storage battery power conditioner 2 independently, or may be configured to control the storage battery power conditioner 2 in accordance with instructions from the control unit 8. Good. The control circuit 20 acquires information on the power detected by the power detection sensor 26.

  Further, the protection relay 23, the interconnection relay 24, and the self-supporting relay 25 have a well-known structure, and details thereof are omitted. Moreover, although it is set as a relay, you may use the switching element which can switch large electric power.

  The power distribution unit 5 is a device that receives power from the storage battery 1 and the commercial power system CS and distributes power to the load system LS or the commercial power system CS to the load system LS and the storage battery 1. The power distribution unit 5 is connected to the power conditioner 2 for power storage, the power receiving unit 6 and the load system LS.

  The power receiving unit 6 includes a power sensor 61 which is a received power detection unit. The power sensor 61 is a sensor that detects power flowing from the commercial power system CS to the power storage system A. The power sensor 61 is connected to the control unit 8, and the detection result (for example, voltage, current, etc.) is sent to the control unit 8.

  The switch 7 is a switch, and is a switch that connects the special load system LSp to either the power distribution unit 5 or the independent relay 25. The switch 7 is always in a state of connecting the power distribution unit 5 and the special load system LSp. When power supply from the power distribution unit 5 side is stopped due to a power failure or the like, the switch 7 is connected to the independent relay 25 side. The switch 7 itself may be configured to detect that power supply from the power distribution unit 5 has been stopped and switch the connection, or may be configured to switch connection according to an instruction from the control unit 8. .

  The control unit 8 is a device that controls the operation of the power storage system A. The control unit 8 is connected to the control circuit 20 of the storage battery power conditioner 2, the breaker 11 of the storage battery 1, the power sensor 61, and the switch 7. And the control part 8 has acquired the information on the electric current flow direction and the electric power value (voltage, electric current) from the electric power sensor 61 at that time. The control unit 8 may include a storage unit (memory) (not shown). The storage unit is connected to the control unit 8 and data necessary for controlling the power storage system A. It is possible to store information from existing devices.

  Below, operation | movement of the electrical storage system A concerning this invention is demonstrated for every some conditions. In the power storage system A, power is supplied to the load system LS (which may be only the special load system LSp) in different modes depending on the state of the commercial power system CS, the received power from the commercial power system CS, the remaining amount of the storage battery 1, and the like. To do. In the following description, connecting the power storage system BS in parallel with the commercial power system LS to a distribution line (here, the distribution unit 5) that distributes power from the commercial power system LS to the load system LS This is referred to as a system (or simply interconnected). Also, releasing the system connection state (disconnecting) is referred to as disconnecting.

  In power storage system A, control unit 8 interconnects power storage system BS according to a predetermined operation mode. Information regarding the operation mode is stored in a storage unit (not shown) provided in the control unit 8.

  Examples of the operation mode of the power storage system A include a grid interconnection operation mode, a charge operation mode, a disconnection mode, and a self-sustaining operation mode. In some cases, other operation modes are provided.

  Below, the operation mode which carries out grid connection is demonstrated. FIG. 2 is a diagram illustrating a state in which the power storage system of FIG. 1 is operated in the grid interconnection operation mode. In FIG. 2, the flow of electricity is indicated by a broken line. Further, in the drawings used in the description of the following operation modes, the flow of electricity is similarly indicated by broken lines.

  The grid interconnection operation mode is a state in which the power storage system BS is grid-connected. As shown in FIG. 2, in the power storage system A, the interconnection relay 24 of the storage battery power conditioner 2 is ON. As a result, the power storage system BS is interconnected.

  In the power distribution unit 5, the power supplied from the power storage system BS and the received power received from the commercial power system CS are combined and supplied to the load system LS. At this time, the switch 7 connects the power distribution unit 5 and the special load system LSp, and the power from the power distribution unit 5 can be supplied to both the normal load system LSs and the special load system LSp. .

  Then, the control circuit 20 of the storage battery power conditioner 2 drives the bidirectional DC / DC converter 21 and the bidirectional inverter 22 to convert the discharge power of the storage battery 1 into alternating current synchronized with the received power received from the commercial power system CS. And sent to the power distribution unit 5.

  By driving the power storage system A in the grid-connected operation mode, part of the power consumed by the load system LS can be covered by the discharge power of the storage battery 1, so that the received power from the commercial power system CS is suppressed. Can do.

  The amount of power supplied from the storage battery 1 is controlled by the control unit 8. The control unit 8 obtains information on the power received from the commercial power system CS from the power sensor 61, and sets the amount of power from the storage battery 1 so that the commercial power system CS falls below a predetermined set power. decide. Thus, by determining the amount of power supplied from the storage battery 1, the received power from the commercial power system CS can be suppressed to a set power or less.

  In Japan, the electricity rate is determined based on the received power. More specifically, the power charge is determined by adding the basic charge and the metered charge determined by the power consumption (received power). The received power from the commercial power system CS is calculated based on a predetermined period (reference period). The basic charge is determined based on the maximum value of the average value (referred to as the maximum peak power) by calculating the average value of the received power in each reference period within a certain past period (for example, one year). .

  In Japan, for many electric power consumers, the time periods when the power consumption of the load system LS is maximum are substantially the same. The maximum peak power of the received power from the commercial power system CS is reduced by supplying the power from the storage battery 1 to the load system LS during that time period and suppressing the received power below the set power (peak cut).

  Further, in the commercial power system CS, it is difficult to finely adjust the supplied power due to the convenience of equipment such as a power plant. In order to prevent the commercial power system CS from being unable to supply power, the commercial power system CS is configured to supply the maximum power to be supplied to the load systems LS of all power consumers. And in many electric power consumers, the generation | occurrence | production time zone of the maximum peak electric power of each electric power consumer substantially corresponds. Therefore, it is possible to suppress the facility expansion of the entire commercial power system CS by supplying the power from the storage battery 1 to the load system LS in the power storage system A and reducing the maximum peak power from the commercial power system CS. .

  Next, a charging operation mode for supplying power to the load system LS while charging the storage battery 1 will be described. FIG. 3 is a diagram illustrating a state where the power storage system of FIG. 1 is operated in the charge operation mode.

  The storage battery 1 discharges the charged electric power and supplements a part of the electric power supplied to the load system LS. Therefore, the storage battery 1 needs to be charged before the power storage system A is operated in the grid connection operation mode. Therefore, the power storage system A operates in the charging operation mode as shown in FIG.

  In the charging operation mode, the interconnection relay 24 of the storage battery power conditioner 2 is ON, and the power storage system BS is grid-connected. Then, the control circuit 20 reverses the bidirectional DC / DC converter 21 and the bidirectional inverter 22 in the grid-connected operation mode, that is, the received power from the commercial power system CS is converted into direct current by the bidirectional inverter 22. Further, the storage battery 1 is charged by being converted into a direct current of a voltage for charging the storage battery 1 by the bidirectional DC / DC converter 21. In the charging operation mode, when there is power demand in the load system LS, a part of the received power from the commercial power system CS is supplied to the load system LS, and the rest is used for charging the storage battery 1.

  As described above, when the demand power of the load system LS is low, that is, when the supply power of the commercial power system CS has a margin, the storage battery 1 is charged and the received power from the commercial power system CS is larger than the set power. When it becomes, the electric power from the storage battery 1 can be supplied to the load system | strain LS, and the maximum peak of received electric power can be disperse | distributed (a peak cut can be performed).

  Furthermore, there is a case where power cannot be supplied from the storage battery 1 due to an insufficient amount of charge of the storage battery 1 or the storage battery 1 is fully charged and no further charging is required. In that case, the power storage system A is operated in the disconnection mode. FIG. 4 is a diagram illustrating a state where the power storage system of FIG. 1 is operated in the disconnection mode.

  As shown in FIG. 4, in the disconnection mode, the power storage system A puts the power storage system BS in a disconnected state. That is, the control circuit 20 of the storage battery power conditioner 2 turns off the interconnection relay 24 and turns off the bidirectional DC / DC converter 21 and the bidirectional inverter 22 to stop the operation of the storage battery power conditioner 2. Thereby, the received power from the commercial power system CS is supplied only to the load system LS.

  In the case of the disconnection mode shown in FIG. 4, the disconnection is performed by turning off the interconnection relay 24. However, the present invention is not limited to this, and when the bidirectional inverter 22 is turned off, When an inverter that cuts the circuit is used, the disconnection mode can be performed by turning off the bidirectional inverter 22 while the interconnection relay 24 is ON. In addition, when the ON / OFF switching of the interconnection relay 24 takes longer than the ON / OFF switching of the bidirectional inverter 22, or when the switching to the disconnection mode is frequently performed, the switching is performed by turning ON / OFF the bidirectional inverter 24. When switching to the row mode and maintaining the release mode for a long time, the interconnection relay 24 may be turned off.

  Further, the commercial power system CS may not be supplied with power to the load system LS due to a power failure or the like. At this time, it is necessary to supply power to at least a device connected to the dedicated load system LSp. Therefore, the power storage system A is operated in the independent operation mode. FIG. 5 is a diagram illustrating a state where the power storage system of FIG. 1 is operated in the self-sustaining operation mode.

  As shown in FIG. 5, when the power storage system A is operated in the self-sustaining operation mode, the power from the storage battery 1 is supplied only to the dedicated load system LSp. Therefore, the control circuit 20 turns off the interconnection relay 24 and puts the power storage system BS in a disconnected state from the power distribution unit 5. Thereby, the electric power from the storage battery 1 does not flow into the power distribution unit 5.

  Then, the control circuit 20 turns on the self-supporting relay 25. By turning on the self-supporting relay 25, the electric power from the storage battery 1 is converted into alternating current by the bidirectional DC / DC converter 21 and the bidirectional inverter 22 and sent to the switch 7.

  In the power storage system A, when the operation mode is switched to the self-sustained operation mode, the switch 7 is also switched from a position where the power distribution unit 5 and the dedicated load system LSp are connected to a position where the independent relay 25 and the dedicated load system LSp are connected. . Thereby, the electric power from the bidirectional inverter 22 is supplied to the dedicated load system LSp through the switch 7. Thereby, even if the received power from the commercial power system CS is delayed due to a power failure or the like, it is possible to supply power to at least the dedicated power system LSp.

  As described above, in the power storage system A, the received power from the commercial power system CS is switched by switching the operation mode according to the remaining charge of the storage battery 1, the demand power amount of the load system LS, and the received power from the commercial power system CS. In addition, it is possible to prevent power from being supplied to at least the dedicated load system LSp.

  The selection of each operation mode of the power storage system A described above is performed by the control unit 8. Below, the process in which the control part 8 selects an operation mode is demonstrated with reference to drawings. FIG. 6 is a flowchart for determining the operation mode.

  As shown in FIG. 1, in the power storage system A, the control unit 8 is connected to the power sensor 61, the control circuit 20, the power detection sensor 26, and the charge amount sensor 12. Then, the control unit 8 receives the received power (current, voltage, etc.) from the commercial power system CS from the power sensor 61, the output power value or input power value of the bidirectional inverter 22 from the power detection sensor 26, and the charge amount sensor 12. The remaining amount of charge of each storage location 1 is acquired.

  The control part 8 acquires the charge remaining amount of the storage battery 1 from the charge amount sensor 12 (step S11). The controller 8 determines whether or not the storage battery 1 is fully charged (step S12). When the storage battery 1 is fully charged (Yes in step S12), the control unit 8 determines that charging of the storage battery 1 is unnecessary, and acquires received power from the power sensor 61 (step S13). The control unit 8 stores a power value set in advance as the maximum value of received power, that is, a set power value, and the control unit 8 detects whether the commercial power system CS has a power failure (step S14). ).

  Usually, the load system LS has standby power and the like, and the demand power does not become zero. That is, the received power from the commercial power system CS does not become zero. Therefore, when the power value acquired from the power sensor 61 is 0, the control unit 8 determines that the commercial power system CS is in a power failure state.

  When the commercial power system CS has a power failure (Yes in step S14), the control unit 8 operates the power storage system A in the self-sustaining operation mode M1 (step S15: see FIG. 5). At this time, the control unit 8 transmits an instruction to turn off the interconnection relay 24 to the control circuit 20 and switches the switch 7.

  When the commercial power system CS is not out of power (No in Step S14), the control unit 8 determines whether the received power is smaller than the set power value (Step S16). Of the control unit 8

  When the received power value is smaller than the set power value (Yes in step S16), the control unit 8 determines that the power supply from the storage battery 1 is unnecessary and operates in the disconnect mode M2 (step S17: (See FIG. 4). When the received power value is equal to or exceeds the set power value (No in step S17), the control unit 8 determines that the power supply from the storage battery 1 is necessary and operates in the grid connection mode M3 (step) S18: See FIG.

  Further, when the storage battery 1 is not fully charged (No in Step S12), the control unit 8 determines whether or not the received power is smaller than the set power value (Step S19). When the received power is smaller than the set power value (Yes in step S19), the control unit 8 determines that the storage battery 1 can be charged and operates in the charging operation mode M4 (see step S110: FIG. 3). ). When the received power is equal to or larger than the set power value (No in step S19), the control unit 8 determines whether or not the storage battery 1 has sufficient remaining charge to supply power to the load system LS. Judgment is made (step S111).

  When the storage battery 1 has a sufficient remaining charge amount that can supply power to the load system LS (Yes in Step S111), the control unit 8 operates in the grid connection mode M3 (Step S18: FIG. 2). reference). Moreover, when the storage battery 1 does not have the charge remaining amount which can supply electric power to the load system | strain LS (when it is No at step S111), the control part 8 drive | operates by the disconnection mode M2 (step S17: refer FIG. 4). .

  And the control part 8 determines the optimal operation mode at that time by performing periodically the process of determining the operation mode shown in FIG.

  As described above, the control unit 8 can finely control the discharging and charging of the storage battery 1 by determining the operation mode based on the amount of power received from the commercial power system CS and the remaining power storage amount of the storage battery 1. In addition, it is possible to efficiently reduce (peak cut) the maximum peak power of the received power from the commercial power system CS.

  Next, the process of determining the amount of charge to the battery 1 when operating in the charge operation mode will be described with reference to the drawings. FIG. 7 is a flowchart showing the determination process of the storage amount in the storage system according to the present invention. 7 is a process performed after the charging operation mode M4 (see FIG. 3) is selected in the above-described operation mode determination process.

  In the normal storage battery 1, the maximum value of chargeable power (charging speed) per unit time is determined. Therefore, in the following description, the charging speed is referred to as chargeable power. Moreover, the power storage capacity to the storage battery 1 can adjust the received power from the commercial power system CS by changing the output of the bidirectional inverter 22 (power information detected by the power detection sensor 26). That is, the output power of the bidirectional inverter 22 corresponds to the charging power supplied to the storage battery 1 among the received power from the commercial power system CS.

  When the charging operation mode M4 is selected in the operation mode determination step, the control unit 8 calculates a difference value between the received power and the set power value (step S21). From the difference value between the received power and the set power value, the charging power value for the storage battery 1 is calculated (step S22). It is determined whether or not the calculated charging power value is larger than the maximum value of the chargeable power to the power storage location 1 (step S23). When the charge power value calculated from the difference between the received power and the set power value is greater than the maximum value of the chargeable power to the storage battery 1 (Yes in step S23), the control unit 8 It is determined whether or not the output is an output (maximum output) when charging the storage battery 1 with the maximum value of chargeable power (step S24).

  When the charging power value (output power value) from the bidirectional inverter 22 is the maximum value of the chargeable power (YES in step S24), the control unit 8 maintains the output of the bidirectional inverter 22 in the control circuit 20. (Step S25). When the charging power value (output power value) from the bidirectional inverter 22 is smaller than the maximum output (No in step S24), the control unit 8 sends the charging power value (output power) from the bidirectional inverter 22 to the control circuit 20. An instruction is sent to control bidirectional inverter 22 so that (value) becomes the maximum value of chargeable power (step S26).

  When the charge power value calculated from the difference value between the received power and the set power value is smaller than the maximum value of the chargeable power to the storage battery 1 (No in step S23), the control unit 8 is bidirectional to the control circuit 20. An instruction to control the charging power value (output power value) from the inverter 22 to be the charging power value calculated from the difference value between the receiving power and the set power value is sent (step S27).

  In this way, the control unit 8 varies the charging power value for the storage location 1 based on the difference between the received power and the set power value, so that the received power is set to the set power value even when the storage battery 1 is charged. It is possible to suppress exceeding.

  Thereby, in the power storage system A, the maximum peak power of the received power is cut by supplying the power from the storage battery 1 to the load system LS, and the maximum peak power of the received power is also cut when the storage battery 1 is charged. Is possible. From this, in the electrical storage system A, it is possible to reduce received electric power reliably.

  The set power value may be contract power of a power consumer having the power storage system A. For example, when actual control is performed, the received power does not exceed the contract power. Therefore, the set power value may be a value with a certain margin with respect to the contract power. As a method of giving a certain margin, for example, a method of multiplying the safety factor can be mentioned. That is, by setting the set power value to a value obtained by multiplying the contract power by a safety factor of about 0.9 or 0.8, even if the received power exceeds the set power value, the received power reaches the contract power. Therefore, it is possible to obtain time for the control unit 8 to change the operation mode of the power storage system A or to change the charging power value of the storage battery 1.

(Second Embodiment)
Another example of the power storage system according to the present invention will be described with reference to the drawings. FIG. 8 is a block diagram showing another example of the power storage system according to the present invention. The power storage system B shown in FIG. 8 includes a plurality of power storage locations 1 and a storage battery power conditioner 2 connected in series for each storage battery 1. The storage battery power conditioner 2 is connected to the power distribution unit 5 in parallel.

  That is, in the power storage system B, a power storage system BS including the storage battery 1 and the storage battery power conditioner 2 is connected to the power distribution unit 5 in parallel. In addition, about the structure of the storage battery 1 and the power conditioner 2 for storage batteries, it has the same structure as the electrical storage system A shown in FIG. 1, The same code | symbol is attached | subjected to the substantially same part, and detailed description of the same part is carried out. Omitted.

  The control unit 8 detects the remaining charge amount of all the storage locations 1, and determines whether or not the total remaining charge amount is smaller than the total remaining charge amount at the time of full charge. When the total remaining charge is smaller than the total remaining charge at full charge, the operation is performed in the charge operation mode. Then, in the charging operation mode, it is determined whether the difference between the received power and the set power value is larger than the sum of the chargeable powers for all the rechargeable batteries 1, and the difference between the received power and the set power value is charged. When it is larger than the sum of the possible powers, the control unit 8 charges all the power storage locations 1 with the maximum value of the chargeable power. Further, when the difference between the received power and the set power value is smaller than the sum of the chargeable power, the chargeable power is adjusted according to each power storage location 1.

  Note that the power or charging power supplied from the rechargeable battery 1 is not necessarily the same and may vary. In this case, the chargeable power to each storage battery 1 may be changed in accordance with the remaining charge of the storage battery 1. Conversely, all the rechargeable batteries 1 may be charged with the same chargeable power, and charging may be stopped from the storage battery 1 that has been charged.

  Even when a plurality of power storage locations 1 are connected in parallel, the power storage system A supplies the power from the storage battery 1 to the load system LS to cut the maximum peak power of the received power and charges the storage battery 1 It is possible to cut the maximum peak power of the received power. From this, in the electrical storage system A, it is possible to reduce received electric power reliably.

(Third embodiment)
A power supply system provided with a power storage system according to the present invention will be described with reference to the drawings. FIG. 9 is a block diagram of a power supply system including the power storage system according to the present invention. The power supply system PWs shown in FIG. 9 is the same as the power supply system shown in FIG. 1 except that it includes a power generation system GS (power generation system), and substantially the same parts are denoted by the same reference numerals. . The power generation system GS includes a solar cell 3 and a solar cell power conditioner 4.

  In the power supply system PWs, the storage battery 1 is connected to the power distribution unit 5 via the storage battery power conditioner 2, and the solar cell 3 is connected to the power distribution unit 5 via the solar battery power conditioner 4. That is, the power storage system BS and the power generation system GS are connected in parallel.

  The solar cell power conditioner 4 includes a DC / DC converter 41, an inverter (DC / AC converter) 42, a protection relay 43, and an interconnection relay 44. In the solar cell power conditioner 4, a DC / DC converter 41, an inverter 42, a protection relay 43, and an interconnection relay 44 are connected in this order from the solar cell 3 side.

  The solar cell 3 is a power generation device that converts sunlight into electrical energy, and since it is well known in the art, its details are omitted. The power generated by the solar cell 3 flows into the DC / DC converter 41 of the solar cell power conditioner 4. The electric power generated by the solar cell 3 is direct current, and the generated voltage varies depending on conditions such as the amount of sunlight and the temperature. The DC / DC converter 41 can convert an input voltage into an arbitrary output voltage. Even when the generated power of the solar cell 3 fluctuates, the DC / DC converter 41 converts it into a constant voltage and outputs it.

  Since the commercial power system CS and the load system LS are alternating current and the output of the DC / DC converter 41 is direct current, the output power from the DC / DC converter 41 can be supplied to the load system LS as it is. It is also impossible to reversely flow into the commercial power system CS. Therefore, the output of the DC / DC converter 41 is converted from direct current to alternating current by the inverter 42. Note that the configurations of the DC / DC converter 41 and the inverter 42 are the same as those conventionally used, and details thereof are omitted.

  The protection relay 43 is a switch that is always ON, and is turned OFF when a large current flows, when an abnormality occurs in the solar cell 3 or the solar cell power conditioner 4, and the circuit constituting the solar cell power conditioner 4 Protect equipment, etc.

  The interconnection relay 44 is a switch that is turned on when the power generated by the solar cell 3 is supplied to the power distribution unit 5. The interconnection relay 44 is normally turned on, and is turned off when the power cannot be received from the commercial power system CS due to a power failure or when the storage battery 1 is charged with the received power from the commercial power system CS. Note that the protection relay 43 and the interconnection relay 44 may be arranged in reverse.

  The solar cell power conditioner 4 includes a control circuit 40 for controlling the DC / DC converter 41, the inverter 42, the protection relay 43, and the interconnection relay 44. The solar cell power conditioner 4 can also perform maximum power point tracking control of the solar cell 3, and the control circuit 40 performs the control. Note that the protection relay 43 and the interconnection relay 44 have a well-known structure and will not be described in detail. Moreover, although it is set as a relay, you may use the switching element which can switch large electric power. Further, the control circuit 20 may be configured to control the solar cell power conditioner 4 independently, or to be configured to control the solar cell power conditioner 4 in accordance with an instruction from the control unit 8. May be.

  The storage battery power conditioner 2 includes a solar battery DC / DC converter 27. The solar cell DC / DC converter 27 is driven when the generated power of the solar cell 3 is directly supplied to the special load system LSp. Since the DC / DC converter 46 operates only when power is supplied from the solar cell 3 to the special load system LSp, the solar cell 3 side is an input, and the special load system LSp side (bidirectional inverter 22 side) is an output. It is a directional converter and has the same configuration as the DC / DC converter 41 attached to the solar cell power conditioner 4.

  In the power supply system PWs having such a configuration, when the solar cell 3 is generating power, the generated power is supplied to the load system LS. And when only the generated electric power of the solar cell 3 cannot suppress the received power from the commercial power system CS below the set power value, the power from the storage battery 1 is supplied to the load system LS. In addition, when performing a self-sustained operation due to a power failure or the like of the commercial power system CS, the generated power of the solar battery 3 can be supplied to the dedicated load system LSp using the solar battery DC / DC converter 27 of the storage battery power conditioner 2. It is possible.

  In the power supply system PWs having such a configuration, when the storage battery 1 is charged with the received power from the commercial power system CS, the power generation system GS is disconnected. This disconnection state includes a method of turning off the interconnection relay 44 and a method of turning off the inverter 42. However, as with the storage battery power conditioner 2, any one of the disconnection states can be performed based on the frequency and switching time of the disconnection state. Such a method may be selected.

  Even in the power supply system PWs having such a configuration, the maximum peak power of the received power is cut by supplying the power from the storage battery 1 and the generated power of the solar battery 3 to the load system LS, and the storage battery 1 It is possible to cut the maximum peak power of the received power when charging. From this, in the electrical storage system A, it is possible to reduce received electric power reliably.

  In the present embodiment, a solar cell is adopted as a power generation device of the power supply system, but is not limited to this, and those that generate power independently, in particular, natural energy, wind power, geothermal heat, etc. Or what was provided with multiple types of these including a solar cell may be sufficient. Moreover, it is also possible to employ | adopt the power generator using a gas turbine, a steam turbine, or both, a fuel cell, etc. as a power generator.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to this content. The embodiments of the present invention can be variously modified without departing from the spirit of the invention.

  The present invention is applied to a power supply system for reducing received power received from a commercial power system, for example, a cogeneration system of an office building or a condominium, a solar power generation system of a general household, a power supply system of a factory, etc. Is possible.

A Power storage system 1 Storage battery 11 Breaker 12 Charge sensor 2 Storage battery power conditioner 20 Control circuit 21 Bidirectional DC / DC converter 22 Bidirectional inverter 23 Protection relay 24 Linkage relay 25 Stand-alone relay 26 Power detection sensor 27 Solar DC / DC converter 3 Solar cell 4 Solar cell power conditioner 41 DC / DC converter 42 Inverter 43 Protection relay 44 Interconnection relay 5 Power distribution unit 6 Power reception unit 61 Power sensor 7 Switch 8 Control unit LS Load system BS Power storage system GS Power generation system CS Commercial power system

Claims (5)

A power storage system that supplies power to a load and is connected between a power reception unit to which a commercial power system is connected and the load,
A power conditioner for power storage that adjusts charging and discharging of the power storage device; and
Received power detection means for detecting received power from the commercial power system;
A control unit,
The control unit obtains received power from the received power detection means, and determines the charging power based on a difference value between the set power value and the received power when the received power is smaller than a preset set power value. And the power storage power conditioner is controlled to charge the power storage device with the charged power. A charge amount detecting means for detecting the charge power and sending the result to the control unit;
The power storage system according to claim 1, wherein the control unit controls the power conditioner for power storage so that the charging power becomes a value determined based on a difference value between the set power value and the received power.   When the charging power value determined by the difference value between the set power value and the received power is larger than the maximum value of the charging power, the control unit charges the power storage device with the maximum value of the charging power. The power storage system according to claim 1, wherein the power conditioner for power storage is controlled. A plurality of power storage systems connected in series with the power storage device and the power conditioner for power storage, and connected in parallel to the power receiving unit,
The power for each power storage so that the sum of the amount of power for charging the power storage device in each power storage system is smaller than the charge power value determined by the difference value between the set power value and the received power. The electrical storage system in any one of Claims 1-3 which controls a conditioner. A power generation system that supplies power to the load and reversely flows power to the commercial power system;
5. The power supply system, wherein the power storage system according to claim 1 is connected to the power reception unit in parallel with the power generation system.

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