JP2019154108A - Power storage system - Google Patents

Abstract

To provide a power storage system which can suppress the supply of an electric power required for equalizing charge from an external power system, and lighten a load on the external power system.SOLUTION: A power storage system 1A comprises: a plurality of power storage units 10 having a lead storage battery 11, a BMU 12 for managing an equalized charge interval of the lead storage battery 11, and a PCS 13 electrically connected between the lead storage battery 11 and an internal power line 2, and serving to charge/discharge the lead storage battery 11; a supervising controller 4 for controlling the action of the PCS 13 of the plurality of power storage units 10; and a power generation unit 20 electrically connected to the internal power line 2, which utilizes a natural energy to generate electric power. The supervising controller 4 collects an electric power required for equalized charge from at least one power storage unit 10 other than the power storage units 10 to be charged equally, and the power generation unit 20.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power storage system.

  Patent Document 1 describes a technique for planning an optimal implementation method for equal charging of a lead storage battery used in a natural energy utilization system. Specifically, the SOC of the lead storage battery is sequentially estimated from the information of the measured state of the lead storage battery and the SOC (State Of Charge) model, and the optimal equal charge is based on the transition of the SOC and the deterioration model of the lead storage battery. Plan the implementation method.

JP 2012-37464 A

  In recent years, power storage systems in which lead storage batteries are connected to a common internal power wiring have been used. Such a power storage system is used for the purpose of stably using unstable generated power in a power generation system using natural energy, for example. By the way, in a power storage system including a lead storage battery, in order to appropriately charge and discharge, the SOC value is continuously measured based on the both-end voltage of the lead storage battery and the charge / discharge amount. However, due to spontaneous discharge of the lead storage battery, the error in the measured SOC value increases little by little over time. Accordingly, in order to accurately measure the SOC value, equal charge (recovery charge) is performed in which the lead storage battery is fully charged periodically (for example, every 1 to 2 weeks). In addition, such a power storage system is operated in a semi-charged state (Partial SOC) so that both charging and discharging can be performed according to the generation state of natural energy. Therefore, unlike a general power storage system in which a lead storage battery is normally fully charged and discharged when necessary, the lead storage battery is not fully charged in a normal operation state. Therefore, the above equal charge is effective for preventing deterioration due to sulfation of the negative electrode due to low SOC.

  However, when the electric power necessary for equal charging is received from the external power system, a load is applied to the external power system. Originally, a power generation system using natural energy was conceived to prevent global warming. Relying on the power supply from the external power system for the power required for the uniform charging is not preferable because it goes against such a purpose.

  The present invention has been made in view of such problems, and provides a power storage system that can suppress the supply of power required for equal charging from an external power system and reduce the load on the external power system. Objective.

  In order to solve the above-described problems, a power storage system according to the present invention includes an internal power wiring electrically connected to an external power system, a lead storage battery, a management unit that manages a uniform charge interval of the lead storage battery, and a lead storage battery. A plurality of power storage units having a charge / discharge control circuit that is electrically connected between the power wiring and the lead storage battery, and an overall controller that controls the operation of the charge / discharge control circuits of the plurality of power storage units; A power generation unit that is electrically connected to the internal power wiring and generates power using natural energy. The overall controller collects electric power necessary for equal charge from at least one other power storage unit and power generation unit other than the power storage unit that performs equal charge.

  In this power storage system, the overall controller collects electric power necessary for equal charge from at least one power storage unit and power generation unit other than the power storage unit that performs equal charge. Thereby, supply from the external electric power system of electric power required for equal charge can be suppressed, and the load on the external electric power system can be reduced.

  In the above power storage system, the overall controller may collect power necessary for equal charge from power storage units having a charge amount equal to or greater than a certain value. Thereby, it can prevent that the charge amount of another electrical storage unit falls too much for equal charge, and can perform normal electric power provision operation | movement other than equal charge appropriately. In this case, the overall controller may postpone or interrupt the equal charge when the charge amounts of all the power storage units other than the power storage unit that performs equal charge fall below a certain value. Thereby, supply from the external electric power system of electric power required for equal charge can be avoided, and the load on the external electric power system can be further reduced.

  ADVANTAGE OF THE INVENTION According to this invention, the electrical storage system which can suppress supply from the external power grid | system of the electric power required for equal charge, and can reduce the load with respect to an external power grid | system can be provided.

FIG. 1 is a diagram schematically illustrating a configuration of a power storage system according to an embodiment. FIG. 2 is a block diagram showing in detail the internal configuration of the management unit of each power storage unit and the internal configuration of the overall controller. FIG. 3 is a graph showing an example of a uniform charging schedule set by the schedule setting unit. FIG. 4 is a diagram schematically illustrating a state in which power necessary for uniform charging is collected. FIG. 5 is a block diagram showing a modification.

  Hereinafter, embodiments of a power storage system according to the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  The power storage system according to the present embodiment is a system that stores electric power generated using natural energy (renewable energy) such as sunlight or wind power. Since natural energy fluctuates greatly depending on the weather and the like, the amount of generated power becomes unstable. In order to supply power stably, this power storage system temporarily stores (charges) the generated power and outputs (discharges) it as necessary. This power storage system can be used in various places such as homes, factories, and farms. An example of a home power storage system is a home energy management system (HEMS).

  FIG. 1 is a diagram schematically illustrating a configuration of a power storage system 1A according to the present embodiment. The power storage system 1 </ b> A includes an internal power wiring 2, a plurality of power storage units 10, one or a plurality of power generation units 20, and an overall controller 4. The plurality of power storage units 10, one or more power generation units 20, and the overall controller 4 are accommodated in, for example, one or more containers. The container is, for example, a cargo container.

  The internal power wiring 2 propagates AC power having a predetermined frequency (for example, a commercial frequency such as 50 Hz or 60 Hz). The internal power wiring 2 is a wiring laid in a limited area in a local area such as a home, a factory, or a farm, and is electrically connected to the load 6. The power storage system 1 </ b> A can supply the power generated by the power generation unit 20 and the power discharged from the power storage unit 10 to the load 6 via the internal power wiring 2. The load is a set of one or more devices or apparatuses that consume power, for example, a set of one or more various electric devices for home use or business use. The internal power wiring 2 is electrically connected to an external power system 3 disposed outside the local area via a linkage point 5.

  The power generation unit 20 is electrically connected to the internal power wiring 2 and generates power using natural energy. The power generation unit 20 includes a power generation device 21 and a power conditioning system (PCS) 22. The power generation device 21 is electrically connected to the internal power wiring 2 via the PCS 22, and generates power using natural energy (renewable energy). The power generation device 21 is, for example, a solar panel or a wind power generation facility, and is installed away from the power generation unit 20. The PCS 22 has an input end connected to the power generation device 21 and an output end connected to the internal power wiring 2. When the power generation device 21 generates DC power, the PCS 22 converts the DC power into AC power having a predetermined frequency and provides it to the internal power wiring 2. Further, when the power generation device 21 generates AC power, the PCS 22 converts the frequency of the AC power into a predetermined frequency and provides it to the internal power wiring 2. The PCS 22 includes an inverter.

  The power storage unit 10 includes a lead storage battery 11, a battery management unit (BMU) 12, and a PCS 13. The lead storage battery 11 stores the power generated by the power generation unit 20. The lead storage battery 11 may consist of a single lead storage battery, or a plurality of lead storage batteries connected in series with each other. The BMU 12 is electrically connected between the lead storage battery 11 and the PCS 13. The BMU 12 is an example of a management unit in the present embodiment, and manages the equal charge interval of the lead storage battery 11. Further, the BMU 12 measures the state of charge (SOC) of the lead storage battery 11 from the integrated value of the current input or output to the lead storage battery 11 and the voltage across the lead storage battery 11. The PCS 13 is electrically connected between the lead storage battery 11 and the internal power wiring 2. The PCS 13 is an example of a charge / discharge control circuit in the present embodiment, and charges and discharges the lead storage battery 11 based on an instruction from the overall controller 4 described later. When discharging the power of the lead storage battery 11 to the internal power wiring 2, the PCS 13 also performs conversion from DC power to AC power having a predetermined frequency. The PCS 13 also performs conversion from AC power to DC power when charging the lead storage battery 11 with the power of the internal power wiring 2. The PCS 13 includes an inverter.

  The overall controller 4 controls the operation (charging operation and discharging operation) of the PCS 13 of each power storage unit 10. When the power consumption of the load 6 exceeds the generated power of the power generation unit 20, the overall controller 4 causes the PCS 13 of each power storage unit 10 to perform a discharging operation. Further, the overall controller 4 causes the PCS 13 of each power storage unit 10 to perform a charging operation when the power consumption of the load 6 falls below the generated power of the power generation unit 20. The overall controller 4 can control the operation of the PCS 13 of each power storage unit 10 based on the SOC value of each lead storage battery 11 provided from the BMU 12. For example, the overall controller 4 does not discharge the lead storage battery 11 whose SOC value is lower than a predetermined value during the discharging operation, and preferentially charges the lead storage battery 11 whose SOC value is lower than the predetermined value during the charging operation. The lead storage battery 11 is operated in a half-charged state (Partial SOC) within a range smaller than a fully charged state and larger than a non-charged state so that both charging and discharging are possible according to the power generation status of the power generation unit 20. Is done. Therefore, the lead storage battery 11 is not fully charged in the normal operation state, unlike the emergency power storage system that normally discharges the lead storage battery when fully charged.

  Here, the equal charging method in the power storage system 1A will be described in detail. FIG. 2 is a block diagram showing in detail the internal configuration of the BMU 12 of each power storage unit 10 and the internal configuration of the overall controller 4. The overall controller 4 and the BMU 12 can be configured by a computer (for example, a microcomputer) including a processor, a memory, and a communication interface. The processor is, for example, a CPU, and the memory is, for example, a flash memory. However, the types of hardware devices that constitute the overall controller 4 and the BMU 12 are not limited to these, and may be arbitrarily selected. Each function of the overall controller 4 and the BMU 12 is realized by the processor executing a program stored in the memory. For example, the processor performs a predetermined operation on the data read from the memory or the data received via the communication interface, and outputs the operation result. Alternatively, the processor stores the received data or calculation result in a memory.

  As shown in FIG. 2, each BMU 12 includes a holding unit 14, a request unit 15, an SOC measurement unit 16, and a communication interface 17. The holding | maintenance part 14 hold | maintains the information 14a of the equal charge interval prescribed | regulated previously for the lead storage battery 11 of the electrical storage unit 10 to which self belongs. The holding unit 14 can be configured by a storage device such as a memory. The uniform charging interval information 14 a is input from the outside of the BMU 12 and stored in the holding unit 14. The equal charging interval varies depending on the internal configuration of the lead storage battery 11 and is, for example, an interval of 7 to 30 days. In one embodiment, the even charging interval is 14 days. In addition, since a suitable equal charge interval changes with specifications, a kind, a magnitude | size, etc. of the lead storage battery 11, the equal charge interval prescribed | regulated previously may differ for every electrical storage unit 10. FIG.

  The request unit 15 reads the uniform charge interval information 14 a stored in the holding unit 14 and knows the prescribed uniform charge interval of the power storage unit 10 to which the request unit 15 belongs. And the request | requirement part 15 of the said electrical storage unit 10 of the said electrical storage unit 10 is N days before the day when the regular equal charging interval passes from the previous equivalent charging day of the electrical storage unit 10 to which it belongs (N is a number smaller than an equal charging interval). A request signal Sa requesting equal charge is output to the overall controller 4 via the communication interface 17. The number of days N is set longer as the number of power storage units 10 increases, and as the time required for uniform charging of each power storage unit 10 increases. In one example, the number of days N is as long as 3 days. The number of days N is set by an instruction from the overall controller 4.

  The SOC measurement unit 16 measures the SOC value of the lead storage battery 11 of the power storage unit 10 to which the SOC measurement unit 16 belongs. The SOC measurement unit 16 outputs information Da related to the measurement result of the SOC value to the overall controller 4 via the communication interface 17.

  Based on the request signal Sa, the overall controller 4 charges the power storage unit 10 evenly within N days. Upon receiving the request signal Sa from the request unit 15 of a certain power storage unit 10, the overall controller 4 causes the PCS 13 of the power storage unit 10 to perform a charging operation for equal charge within N days. As shown in FIG. 2, the overall controller 4 includes a communication interface 41, a schedule setting unit 42, and a PCS control unit 43. The communication interface 41 is connected to the communication interface 17 of each power storage unit 10 by, for example, a wired or wireless data communication method. The communication interface 41 receives the request signal Sa from the communication interface 17 of each power storage unit 10. The schedule setting unit 42 sets a schedule for equal charging of each power storage unit 10 based on the request signal Sa obtained via the communication interface 41. For example, when there is only one power storage unit 10 that has output the request signal Sa, the schedule setting unit 42 schedules the power storage unit 10 to perform equal charge immediately. When there are two or more power storage units 10 that output the request signal Sa, the schedule setting unit 42 schedules the power storage units 10 to perform equal charge in order. The schedule setting unit 42 provides the PCS control unit 43 with information related to the set equal charge schedule. Based on the information provided from the schedule setting unit 42, the PCS control unit 43 causes the PCS 13 of each power storage unit 10 to perform a charging operation for equal charging.

  FIG. 3 is a graph showing an example of a uniform charging schedule set by the schedule setting unit 42. In FIG. 3, the horizontal axis indicates the number of days elapsed. In this figure, as an example, a schedule for equal charging of three power storage units 10 (shown as power storage units A to C in the figure) is shown, but the number of power storage units 10 may be two, or four or more. But you can. In this example, first, at a certain timing T <b> 1, a request signal Sa is transmitted from the request unit 15 of a certain power storage unit A among the plurality of power storage units 10 to the overall controller 4. At this time, since there is no other power storage unit 10 that outputs the request signal Sa, the schedule setting unit 42 schedules the power storage unit A to start charging immediately (or after a predetermined period). The PCS control unit 43 is instructed to perform equal charge based on the schedule. When receiving the instruction from the schedule setting unit 42, the PCS control unit 43 starts the equal charge A1 of the power storage unit A. Next, when the request signal Sa is transmitted from the request unit 15 of another power storage unit B to the general controller 4 during the equal charge of the power storage unit A (timing T2 in the figure), the general controller 4 The schedule is reconfigured so that the equal charge of the power storage unit B is started after the equal charge of A is completed. When the request signal Sa is transmitted from the request unit 15 of another power storage unit C to the general controller 4 during the equal charge of the power storage unit A (timing T3 in the figure), the general controller 4 The schedule is reassembled so that the equal charge of the power storage unit C is started after the equal charge of B is completed. The PCS control unit 43 performs the equal charge A2 of the power storage unit B after completing the equal charge A1 of the power storage unit A, and performs the equal charge A3 of the power storage unit C after completing the equal charge A2 of the power storage unit B. To do.

  Here, a power supply source for equal charge will be described. In the present embodiment, the overall controller 4 collects electric power necessary for equal charge from at least one other power storage unit 10 and the power generation unit 20 excluding the power storage unit 10 that performs equal charge. FIG. 4 is a diagram schematically illustrating a state in which power necessary for uniform charging is collected. In FIG. 4, the power storage system 1 </ b> A includes, for example, five power storage units 10 </ b> A to 10 </ b> E as the plurality of power storage units 10. Here, the power storage unit 10 </ b> C is an object of equal charge. The hatching in the figure schematically shows the state of charge of the lead storage battery 11 of each power storage unit 10.

  When the overall controller 4 performs equal charge of the power storage unit 10C, first, the overall controller 4 preferentially supplies the power P1 generated in the power generation unit 20 to the power storage unit 10C. When the power P1 generated in the power generation unit 20 is insufficient, the overall controller 4 uses the power charged in at least one power storage unit 10 other than the power storage unit 10C (for example, the power storage units 10A, 10B, and 10D). A part of the power P2 to P4 is supplied to the power storage unit 10C for equal charging. The magnitudes of the electric powers P2 to P4 are set to a very small amount so as not to disturb the normal discharging operation of the power storage units 10A, 10B, and 10D for supplying electric power to the load 6.

  At this time, based on the information Da from the BMU 12, the overall controller 4 collects electric power P2 to P4 necessary for equal charge from the power storage units 10A, 10B, and 10D whose charge amount (SOC value) is equal to or greater than a certain value SOC1, The electric power of the power storage unit 10E whose charge amount is equal to or less than a certain value SOC1 is not used for equal charge. The constant value SOC1 is a preset value and is held in a storage device (memory or the like) of the overall controller 4. The constant value SOC1 is, for example, 15% to 30%. In addition, the overall controller 4 postpones or interrupts the equalization charge when the charge amount of all the other power storage units 10 except the power storage unit 10 that performs the equal charge falls below a certain value SOC1. Then, after the time has elapsed and the charge amount of at least one other power storage unit 10 has exceeded a certain value SOC1, uniform charging is started or resumed.

  Further, the overall controller 4 may postpone or interrupt the uniform charging when the power generation amount of the power generation unit 20 falls below a certain value. And after time passes and the electric power generation amount of the electric power generation unit 20 exceeds a fixed value, you may start or restart equal charge.

  Further, the overall controller 4 determines at least one of the voltage and current of equal charge based on the charge amount of all the other power storage units 10 except the power storage unit 10 that performs equal charge and the power generation amount of the power generation unit 20. The size may be adjusted. That is, when the charge amount of all the other power storage units 10 and the power generation amount of the power generation unit 20 are small, the overall controller 4 reduces at least one of the equal charge voltage and current, When the charge amount of the unit 10 and the power generation amount of the power generation unit 20 are large, at least one of the voltage and current for equal charge may be increased.

  The effects obtained by the power storage system 1A according to the present embodiment described above will be described. In this power storage system 1 </ b> A, the overall controller 4 collects at least a part of the power necessary for the equal charge from at least one other power storage unit 10 and the power generation unit 20 except the power storage unit 10 that performs the equal charge. Thereby, supply from the external electric power system 3 of electric power required for equal charge can be suppressed, the load on the external electric power system 3 can be reduced, and at the same time, the purchase amount of electric power from the external electric power system 3 can be reduced.

  Further, as described above, the overall controller 4 may collect power necessary for uniform charging from the power storage unit 10 whose charging amount is equal to or greater than the predetermined value SOC1. Thereby, it can prevent that the charge amount of the other electrical storage unit 10 falls too much for equal charge, and can perform normal electric power provision operation | movement other than equal charge appropriately. Further, in this case, the overall controller 4 may interrupt the equal charge when the charge amount of all the other power storage units 10 excluding the power storage unit 10 that performs the equal charge falls below a certain value SOC1. Thereby, supply from the external electric power system 3 of electric power required for equal charge can be avoided, and the load on the external electric power system 3 can be further reduced.

  In the present embodiment, since the request signal Sa for requesting equal charge is provided from the BMU 12 of each power storage unit 10 to the general controller 4, the general controller 4 does not need to follow a predetermined equal charge schedule. The equal charge timing of each power storage unit 10 may be determined based on these request signals Sa. Further, since the request signal Sa from the BMU 12 of each power storage unit 10 is provided in advance to the general controller 4 N days before the specified equal charge interval elapses, the general controller 4 The equal charging timing of each power storage unit 10 can be determined with a margin while suppressing duplication of timing. Therefore, according to the power storage system 1A of the present embodiment, it is possible to easily manage the schedule for equal charge. In addition, the overall controller 4 only needs to determine the equal charge timing of each power storage unit 10 based on the request signal Sa from each power storage unit 10, so even when a new power storage unit 10 is added, it is necessary to reconfigure the schedule from scratch. Thus, the new power storage unit 10 can be charged evenly without stopping the operation of the power storage system 1A. Further, even when the power generation unit 20 that generates power using natural energy is provided as in the present embodiment and the generated power amount becomes unstable, the equal charge timing is dynamically changed during system operation. Thus, the operating efficiency of the power storage system 1A can be improved.

  Further, as described above, the equal charging intervals of at least two power storage units 10 among the plurality of power storage units 10 may be different from each other. In such a case, assuming that a schedule for equal charge is determined in advance, when the number of power storage units 10 increases, the schedule management for equal charge and the reorganization of the schedule become extremely complicated. The power storage system 1A of the present embodiment is particularly effective in such a case.

  Further, as in the present embodiment, the number of days N may be set longer as the number of power storage units 10 increases. Thereby, even if the number of power storage units 10 increases, the equal charge timing of each power storage unit 10 can be set with a margin. In other words, the number of days N may be set shorter as the number of power storage units 10 decreases. Thereby, the schedule management of the general controller 4 can be further facilitated.

(Modification)
FIG. 5 is a block diagram showing a modification of the above embodiment. The power storage system of this modification includes a general controller 4A instead of the general controller 4 of the above embodiment. Since other configurations are the same as those in the above embodiment, the description thereof is omitted.

  As shown in FIG. 5, the overall controller 4 </ b> A of this modification further includes a natural energy fluctuation prediction unit 44 in addition to the communication interface 41, the schedule setting unit 42, and the PCS control unit 43. The natural energy fluctuation prediction unit 44 predicts a situation related to fluctuations in natural energy such as weather fluctuations or inputs information related to fluctuation prediction of natural energy from outside the power storage system 1A. Then, the overall controller 4A sets the number of days N based on the natural energy fluctuation prediction. For example, when the power generation device 21 is a solar panel, the amount of generated power decreases when a cloudy or rainy day continues. Therefore, if cloudy or rainy days continue, the number of days N is set longer than normal (for example, if the normal number of days N is 3 days, the number of days N is changed to 4 days, etc.), and the schedule has room. It is good to make it.

  As in the present modification, the number of days N may be a value set based on natural energy fluctuation prediction. Thereby, it is possible to give a margin to the uniform charging schedule of each power storage unit 10 in consideration of the increase or decrease in the amount of generated power in the power generation unit 20.

  The power storage system according to the present invention is not limited to the above-described embodiment, and various other modifications are possible. For example, in the above embodiment, the case where the equal charge of the power storage units is performed one by one (the equal charge of two or more power storage units is not performed repeatedly) is not limited to this example. Duplicate equal charging may be performed. Further, in the above embodiment, the case where the BMU requests uniform charge from the general controller is illustrated. However, the present invention is not limited to this example, and the general controller manages information related to a predetermined uniform charge schedule of all power storage units. Based on this information, the general controller may instruct equal charge of each power storage unit.

  DESCRIPTION OF SYMBOLS 1A ... Power storage system, 2 ... Internal power wiring, 3 ... External power system, 4, 4A ... General controller, 5 ... Linkage point, 6 ... Load, 10, 10A-10E ... Power storage unit, 11 ... Lead storage battery, 12 ... Battery Management unit (BMU), 13, 22 ... Power conditioning system (PCS), 14 ... Holding unit, 15 ... Requesting unit, 16 ... SOC measuring unit, 17, 41 ... Communication interface, 20 ... Power generation unit, 21 ... Power generation device, 42 ... Schedule setting unit, 43 ... PCS control unit, 44 ... Natural energy fluctuation prediction unit, P1-P4 ... Electric power, Sa ... Request signal, T1-T3 ... Timing.

Claims (3)

Internal power wiring electrically connected to the external power system;
A plurality of lead storage batteries, a management unit that manages an equal charge interval of the lead storage battery, and a charge / discharge control circuit that is electrically connected between the lead storage battery and the power wiring and charges and discharges the lead storage battery Storage unit of
An overall controller for controlling the operation of the charge / discharge control circuit of the plurality of power storage units;
A power generation unit that is electrically connected to the internal power wiring and generates power using natural energy;
With
The overall controller collects electric power required for equal charge from at least one other power storage unit and the power generation unit other than the power storage unit that performs equal charge.   2. The power storage system according to claim 1, wherein the overall controller collects electric power necessary for equal charge from the power storage units having a charge amount equal to or greater than a predetermined value.   3. The power storage system according to claim 2, wherein the overall controller postpones or interrupts the uniform charging when a charge amount of all the power storage units other than the power storage unit that performs equal charge is lower than the certain value.

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