JP3827676B2 - Power storage system - Google Patents

Description

The present invention makes it possible to reduce the electricity bill and level the load by using the contract menu for each time zone of the power company, storing the nighttime power, and discharging it in a time zone other than the nighttime power supply time zone. In addition, the present invention relates to a power storage system that can store solar power generation, wind power generation, and the like and contribute to CO ₂ reduction.

  In electric power companies, power generation is controlled by predicting power demand by setting power generation capacity by nuclear power, hydropower, thermal power generation, etc. so that it can cope with peak power consumed during daytime or at specific times. is doing. The demand for electric power is increasing in urban areas, and the increase in peak electric power has led to an increase in the burden of constructing new power generation facilities. On the other hand, at night, the power usage rate decreases because the power usage in factories and offices decreases. A nighttime electricity use discount discount system is being implemented to equalize the large gap between daytime and nighttime electricity demand. Nighttime electricity is cheaper than daytime electricity and has a low use rate of fossil fuels, so it emits less carbon dioxide and is convenient for global environmental conservation.

  There are two methods for using nighttime electricity: a method of storing power itself, a method of storing it by converting it into thermal energy such as hot water supply equipment and ice heat storage, or a method of storing it as location energy, such as pumped-storage power generation. It is considered. Among them, a typical method for storing power is a power storage system that stores nighttime power in a storage battery and consumes the power from the storage battery during daytime when the power load is large. According to this power storage system, there is an effect of reducing the electricity usage fee for the consumer, and it is possible to level the power system at the bottom-up at night and by suppressing peak power during the daytime.

However, it naturally occurs that daytime power consumption is larger than the capacity of the storage battery.
As a countermeasure when such a power supply exceeding the storage capacity is performed on the load, it is disclosed in, for example, Japanese Patent Application Laid-Open No. 2000-308282 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2000-295784 (Patent Document 2). If the system switching means is provided and the load exceeds the capacity of the storage battery, the power supply to the load is switched from the storage battery to the commercial power.

  As another countermeasure, for example, as disclosed in Japanese Patent Application Laid-Open No. 2001-008385 (Patent Document 3), several types of storage battery discharge patterns for one day are stored in advance, and the user selects the pattern appropriately. By doing so, there is an electric power storage system that uses the nighttime electric power charged in the storage battery effectively and without waste.

  Japanese Patent Application Laid-Open No. 10-201129 (Patent Document 4) and Japanese Patent Application Laid-Open No. 10-201130 (Patent Document 5) disclose the use of solar cells for daytime charging of storage batteries.

JP 2000-308282 A JP 2000-295784 A JP 2001-008385 A JP-A-10-2011129 JP-A-10-201130

  As described above, in the power storage systems proposed in Patent Documents 1 to 5, when the stored power of the storage battery connected to the load is reduced, it becomes impossible to meet the power demand of the load. Is supplying power. However, there has been a situation where the power stored in the cheap nighttime electricity rate zone cannot be used up effectively, and the power of the daytime electricity rate has been used, and the purpose of the power storage system has not been sufficiently achieved.

  Therefore, the present invention can suppress the effective use of nighttime power and the use of daytime power by effectively using the power stored in the power storage means even when there is a power demand exceeding the output capacity from the load. An object of the present invention is to provide a power storage system that can be used.

  In order to solve the above problems, a power storage system of the present invention includes a rectifying unit that converts commercial power into DC power, a power storage unit that stores rectified DC power, and a DC power stored in the power storage unit. Power conversion means for converting into AC power substantially equal to the voltage and frequency of commercial power, and power selection means for selectively supplying the commercial power and the AC power converted by the power conversion means to a load by switching a plurality of switches And control means for controlling a plurality of switches of the power selection means, and the control means supplies power from the commercial power to the power storage means via the rectification means during night charge application time zone In addition, in the night operation mode in which power is supplied to the load, and in a time zone other than the night charge application time zone, the storage is performed when the power consumption of the load is less than a predetermined value. A discharge operation mode for supplying power to the load only from the means, and when the power consumption of the load is equal to or greater than the predetermined value, the power consumption up to the predetermined value is supplied from the power storage means, Power consumption equal to or greater than a predetermined value controls the plurality of switches according to each mode of the system supplement operation mode in which power is supplied from the commercial power.

  In the present invention, when discharging from the power storage means other than the night charge applicable time zone, even when there is a power request from the load more than the output capacity, by effectively using the power stored in the power storage means, Effective use of nighttime power and daytime power can be suppressed.

  By making the rectifying means and the power conversion means a bidirectional power converter having both functions, the power storage means operates as a converter during the charging operation, and discharges power from the power storage means to the load. During operation, it is controlled to operate as an inverter.

  The power selection means includes a first switch connected between commercial power and the power conversion means, a second switch connected between commercial power and a load, the power conversion means, and the first switch. The power conversion means is always connected to the load, and the control means switches the switches and electronic switch means according to the modes. As a result, power from two power sources can be supplied to the load in parallel.

  Further, by providing an electronic switch means for cutting off the commercial power from the power conversion means and the commercial power side on the commercial power side of the connection point between the output section of the power storage means and the commercial power, the output of the power storage means and the commercial power are supplied during the commercial power supply. The electric power is supplied to a predetermined load while sharing the current at the same time, a power failure of the commercial power is detected, the electronic switch means is immediately opened, and the output control of the power storage means can be operated independently. The load current can be controlled to be supplied by the power storage means. As a result, it is possible to prevent a reverse power flow to the commercial system that occurs when the power storage means is operated independently.

A disaster can be prevented by providing a breaker between the power conversion means and the power storage means to prevent a short circuit and further providing a ground fault detection means for ground fault protection. Further, a fuse is provided between the transformer and the power conversion means to prevent short circuit.
By providing the temperature sensor, temperature management of the power storage means is performed, and the power storage means is protected by stopping the operation of the power storage system when an abnormality occurs. This temperature management can also be used for charge / discharge voltage management.
It said storage means, photovoltaic, can be configured to supply power from an external power generating means such as a wind power, thereby to suppress the generation of CO ₂ it is possible to improve the global environment.

  As described above, according to the present invention, when the power consumption of the load is greater than or equal to the predetermined value in the time zone other than the nighttime charge application time zone, the commercial power and the power supply from the power storage means to the load By providing a function to perform the power in parallel, even when there is a power demand exceeding the output capacity from the load, by effectively using the power stored in the power storage means, it is possible to effectively use nighttime power and daytime power. Can be suppressed.

  By making the rectifier means and the power converter means a bidirectional power converter having both functions, it operates as a converter during the charging operation of the power storage means, and also during the discharge operation of power from the power storage means to the load. Is controlled to operate as an inverter.

  By configuring the power selection means with the first and second switches and the electronic switch means, it is possible to supply power from two power sources in parallel to the load.

  By providing electronic switch means for cutting off commercial power between commercial power and providing a power failure detection means on the commercial power side, when a power failure occurs on the commercial power side, opening the electronic switch means, It is possible to prevent the reverse power flow to the commercial system that occurs when the power storage means is operated independently.

  Hereinafter, embodiments of the power storage system of the present invention will be described with reference to FIGS.

  FIG. 1 is a block diagram (single line diagram) showing a configuration of an embodiment of a power storage system according to the present invention. In the figure, the power storage system of the present embodiment includes a distribution board 10 that receives power from commercial power, a power selection means 1 that switches power supply from a storage battery 30 constituting the power storage means 3 to a load 40, and a distribution board. Bidirectional power conversion having both functions of a converter that converts AC power (commercial power) from 10 into DC power for charging the storage battery 30 and an inverter that converts DC power stored in the storage battery 30 into AC power 2, a storage unit 3 including a storage battery 30, and a control unit 4 that controls the power selection unit 1 and the bidirectional power converter 2. In the figure, 11 is an earth leakage breaker that cuts off when overloading and circuit leakage, 12 is a noise filter that removes low-order switching noise from the bidirectional power converter 2, 16 is a temperature sensor of the heat sink, 17 is a smoothing capacitor, 18 is a battery voltage detector, 19 is a circuit breaker that is opened when the power storage means 3 fails or is inspected, and 22 is a DC ground fault detector that protects against ground faults and prevents disasters caused by earth leakage. is there. The temperature sensor 16 transmits heat sink temperature information to the control unit 4, and the control unit 4 stops the bidirectional power converter 2 when the temperature is abnormal, thereby protecting the bidirectional power converter 2.

  The power selection means 1 includes two systems of changeover switches MS1 and MS2 and electronic switches Q5 and Q6 formed of switching elements such as thyristors. The changeover switches MS1 and MS2 are controlled to be opened and closed by a magnet switch 5. The magnet switch 5 and the electronic switches Q5 and Q6 are controlled by the control means 4.

  The main converter of the bidirectional power converter 2 is constituted by the switching element 15 so that it operates as a converter during the charging operation of the storage battery 30 and when power is supplied from the storage battery 30 to the load 40 in a discharging operation. It is controlled by the control means 4 and the switching drive unit 6 so as to operate as an inverter. By controlling the switching element 15 in this way, the alternating current waveform of the bidirectional power converter 2 is controlled to coincide with the sine wave of the commercial voltage, thereby enabling bidirectional power conversion that can be charged and discharged.

Specifically, the following switching control is performed.
(1) Enter the switching element 15 and give a switching command to perform a switching operation to make the input voltage pulsed.
(2) Control is performed so that this pulse becomes a sine wave in an arbitrary interval.
(3) This sine wave is converted to a direct current by smoothing the waveform generated by switching by the capacitor 17 during charging, and the output voltage is changed to a sine wave during discharging.
(4) This control enables bidirectional power conversion in the bidirectional power converter 2.

  Further, when the pulse width during switching control is increased, the current and voltage increase, and when the pulse width is decreased, the current and voltage decrease. The power storage means 3 is charged with a constant current with an arbitrary current. When the amount of electricity is close to charging, the pulse width is reduced to reduce the charging current, and charging is performed until the amount of charging electricity is completed. In this manner, the charging current value is controlled step by step to control the optimum amount of electricity stored in the storage battery 30. The discharge power and the load power can be monitored, the pulse width can be changed, and the inverter output voltage can be changed to control the discharge of the power storage means 3.

(1) Enter the switching element 15 and give a switching command to perform a switching operation so that the input voltage is pulsed.
(2) On / off operation is performed in an arbitrary section (67 μS in this configuration). The current value in an arbitrary section is determined by utilizing the fact that the current increases when the element is on and decreases when the element is off. This current value increases as the on-state pulse width of an arbitrary section is increased, and conversely decreases as the pulse width decreases. By utilizing this, the pulse width is controlled so that the current value becomes a sine wave in the entire arbitrary section.
(3) During charging, the pulse waveform is smoothed by the smoothing capacitor 17 to charge the live battery as a direct current. When discharging, the same frequency as the commercial frequency is supplied to the load. Furthermore, when performing a system replenishment operation from commercial power, inverter output is performed in synchronization with the commercial frequency.
(4) The bidirectional power converter 2 enables bidirectional power conversion by these controls.

  The bidirectional power converter 2 is provided with a smoothing capacitor 17 and charges the storage battery 30 by smoothing the charging current. In addition, a transformer 14 is provided between the power selection unit 1 and the bidirectional power converter 2 so that the voltage is reduced when the storage battery 30 is charged and increased when the storage battery 30 is discharged. In addition, this transformer leak reactance is used to form a filter with the capacitor 13 to reduce higher-order harmonics generated during power conversion by the bidirectional power converter 2.

The power storage means 3 is provided with a temperature sensor 21 that detects the temperature of the storage battery 30. This temperature sensor 21 transmits temperature information of the storage battery 30 to the control means 4. When the temperature is abnormal, the bidirectional power converter 2 is stopped to protect the battery. Further, the temperature information is used as a voltage control value performed by the control means 4 at the time of charging / discharging.
The storage battery 30 can also be connected to external power generation means 20 such as solar power generation, wind power generation, or a hydrogen battery. Thereby, it is possible to store solar power, wind power, etc., which are natural energy, and to contribute to CO ₂ reduction by using a hydrogen battery, etc., which is clean energy.

  The control means 4 is constituted by a CPU in this embodiment, and controls each switch of the power selection means 1 based on the voltage and current of commercial power, the output voltage and current, the voltage of the storage battery, and the time information of the internal timer. In addition, the inverter function and the converter function of the bidirectional power converter 2 are controlled.

  FIG. 2 shows the operation status of the switch of the power selection means 1 in each operation mode. In the commercial operation and charging operation modes, the changeover switch MS1 and the electronic switch means Q5, 6 are closed. Since the bidirectional power converter 2 is not operated in the commercial operation mode, power is only supplied to the load side. In the charging operation mode, the bidirectional power conversion device 2 is operated as a converter for charging, so that power is supplied to the storage battery 30 and the load. In the discharge operation mode, since the electronic switch means Q5 and 6 are opened, power is fed only from the bidirectional converter device 2.

  In the system replenishment operation mode, the changeover switch MS1 and the electronic switch means Q5, 6 are closed, but the control means 4 supplies power from the storage battery 30 up to a certain value (for example, 1.5 kVA). Control is performed so that the above shortage of power consumption is supplied from commercial power. This control is performed by the control means 4 by monitoring the output voltage to the load 40, the output current, and the inverter current from the bidirectional converter 2.

  Next, the operation in the present embodiment will be described using the flowcharts of FIGS. 3 to 7 and the system connection diagrams of FIGS.

1. Steady operation In step 100 shown in FIG. 3, it is determined whether or not it is a discharge start time zone, that is, a time zone other than the night charge time zone. This is possible by measuring time using a timer (not shown) inside the CPU of the control device 4. If it is the discharge start time zone, it is determined in step 110 whether or not the discharge start condition is satisfied. In this example, the discharge start conditions are the remaining battery power, the storage battery temperature, and the discharge time zone.

  If the condition is satisfied, it is determined in step 120 whether the load power is equal to or greater than a set value (1.5 kVA in this example). If it is less than the set value, the changeover switch MS1 and the electronic switches Q5, 6 of the power selection means 1 are opened in step 130, and the discharge operation mode is set only from the storage battery 30 (FIG. 10). If the load power is greater than or equal to the set value (1.5 kVA in this example), in step 140, all of the selector switch MS1 and the electronic switches Q5 and 6 of the power selection means 1 are turned on to supply commercial power for the discharge operation. The replenishment operation mode is set (FIG. 11). When the operation mode is determined, discharge operation output control in step 150 is performed.

  In step 160, the discharge operation continuation conditions such as the remaining battery capacity, storage battery temperature, and discharge time zone are monitored. If not established, in step 170, the discharge operation is stopped and the discharge amount recording process is performed. For this, the discharge amount monitoring process in step 180 is always performed. In step 190, the changeover switch MS1 of the power selection means 1 is closed, and the electronic switches Q5 and 6 are closed, thereby switching the power distribution to the commercial operation (FIG. 8).

2. Unsteady operation When a power failure occurs in step 200 shown in FIG. 4, the current operating state is determined in step 210. If it is in the charging mode, in step 220, a non-stationary process is performed during charging operation. If it is in the discharge mode (including the system replenishment operation mode), in step 230, non-stationary processing during discharge operation is performed. If the operation mode is the commercial operation mode, in step 240, unsteady processing during commercial operation is performed. In step 250, the depth of discharge is determined. If the depth of discharge is exceeded, the equal charge request flag is set at step 260.

That is,
(1) In unsteady operation, the power storage capacity is reduced by supplying power from the storage battery to the load, and the operation of step 260 is executed when the depth of discharge is reached. During this time, commercial use is out of service.
(2) When commercial power returns from a power failure, the system shifts from unsteady operation to steady operation (commercial operation). If the flag is set at this time, charging is performed during the charging time period.
In step 270, the occurrence of a power failure is recorded. (Fig. 12)

3. Charge control (1)
In step 300 shown in FIG. 5, it is determined whether it is a charging time zone. If it is in the charging time zone, it is determined in step 310 whether charging is necessary. If charging is required, in step 310, the changeover switch MS1 and the electronic switches Q5, 6 of the power selection means 1 are turned on and the bidirectional power converter 2 is turned on. And charging from commercial power (FIG. 9).

4). Battery Temperature Monitoring In step 400 of FIG. 6, the temperature at the start of charging is recorded. In step 410, the current battery temperature value measured by the temperature sensor 21 is compared with the temperature at the start of charging.
In step 420, it is determined whether charging has been completed. If charging has not been completed, it is determined whether there has been a temperature increase of 6 ° C. or more. If there is a temperature increase, a charge stop flag is set in step 440 to stop charging. To do.

5). Charge control (2)
In step 500 of FIG. 7, battery voltage detection and battery temperature detection processing are performed. In step 510, various charging amounts are set.
Here, the various charging amounts refer to current value settings when charging is performed by gradually reducing the charging current value until the amount of charging electricity is reached when performing the charging operation.
Next, constant current charging is performed in step 520. In step 530, it is determined whether or not the amount of charged electricity has been reached. If it has been reached, battery voltage determination processing is performed in step 540.

  The present invention stores electric power at night and discharges it in a time zone other than the supply time zone of night electric power, thereby reducing the electricity bill and leveling the load. It can be used as an electric power storage system in which a power source by other external power generation means can be charged as it is or converted into direct current and charged.

1 is a block diagram (single line diagram) showing a configuration of an embodiment of a power storage system according to the present invention. It is a table which shows the operation condition of the switch of the electric power selection means in each operation mode in embodiment of this invention. It is a flowchart which shows operation | movement of the control means in embodiment of this invention. It is a flowchart which shows operation | movement of the control means in embodiment of this invention. It is a flowchart which shows operation | movement of the control means in embodiment of this invention. It is a flowchart which shows operation | movement of the control means in embodiment of this invention. It is a flowchart which shows operation | movement of the control means in embodiment of this invention. It is explanatory drawing of each operation mode in embodiment of this invention. It is explanatory drawing of each operation mode in embodiment of this invention. It is explanatory drawing of each operation mode in embodiment of this invention. It is explanatory drawing of each operation mode in embodiment of this invention. It is explanatory drawing of each operation mode in embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electric power selection means 2 Bidirectional power converter 3 Power storage means 4 Control means 5 Magnet switch 6 Switching drive part 10 Distribution board 11 Earth leakage breaker 12 Noise filter 13 Capacitor 14 Transformer 15 Switching element 16 Temperature sensor 17 Smoothing capacitor 18 Battery voltage detection 19 Breaker 20 External power generation means 21 Temperature sensor 22 DC ground fault detector 23 Fuse 30 Storage battery 40 Load

Claims (6)

Rectifying means for converting commercial power into DC power, power storage means for storing the rectified DC power, and power for converting DC power stored in the power storage means into AC power substantially equal to the voltage and frequency of the commercial power Conversion means, power selection means for selectively supplying the commercial power and AC power converted by the power conversion means to a load by switching a plurality of switches, control of the plurality of switches of the power selection means, and the load Output voltage, output current to, control means for monitoring the current from the power conversion means , and a power failure detection means provided on the commercial power side ,
The control means includes a night operation mode for supplying power from the commercial power to the power storage means via the rectifying means and supplying power to the load during the night charge application time zone, and other than the night charge application time zone. In a time zone, when the power consumption of the load is less than a predetermined value, a discharge operation mode for supplying power to the load only from the power storage means, and when the power consumption of the load is greater than or equal to the predetermined value The power consumption up to the predetermined value is supplied from the power storage means, and the power consumption greater than the predetermined value is supplied from the commercial power. Control,
The power selection means includes a first switch connected between commercial power and the power conversion means, a second switch connected between commercial power and a load, the power conversion means, and the first switch. The power conversion means is always connected to the load, and the control means switches the switches and the electronic switch means as follows . A power storage system characterized by that.
(1) Night operation mode
The first switch is closed, the electronic switch is closed, and the second switch is opened.
(2) Discharge operation mode
The first switch is closed, the electronic switch is opened, and the second switch is opened.
(3) System replenishment operation mode
The first switch is closed, the electronic switch is closed, and the second switch is opened.
(4) When a power failure occurs
The first switch is open, the electronic switch is open, and the second switch is open.
(5) Device failure
When the control means determines that the device has failed or an overcurrent has occurred based on the output voltage to the load monitored by the control means, the output current, and the current from the power conversion means, the first switch is opened, The electronic switch opens and the second switch closes.
  The power storage system according to claim 1, wherein the rectifying means and the power conversion means are bidirectional power converters having both functions. The power storage system according to claim 1 or 2 , further comprising an electronic switch unit that cuts off the power conversion unit and the commercial power on the commercial power side of a connection point between the output unit of the power storage unit and the commercial power. The power storage system according to any one of claims 1 to 3 , wherein a ground fault detection unit for ground fault protection is provided between the power conversion unit and the power storage unit. By providing the temperature sensor, performs temperature control of the storage means, the abnormal time by stopping the operation of the power storage system, any one of claims 1-4, characterized in that for protecting the storage means The power storage system according to the section. The power storage system according to any one of claims 1 to 5 , wherein the power storage unit is configured to supply electric power from an external power generation unit such as solar power generation or wind power generation.

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